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📞 Connecting a Provider Number

🇩🇰 Denmark: SIP providers and number connection

Where to get a number with a SIP trunk in Denmark, which parameters providers issue and what to enter in the admin panel so the number rings in the PBX

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Denmark: SIP providers and connecting a number to the PBX

This page continues the general guide to connecting a provider's number to the PBX: that page covers what is the same for every carrier — the two trunk modes, what to ask the provider, what to enter in the form, network requirements and how to test the link. Here is the Danish part: who sells a number with a SIP trunk in the country, what that carrier issues and what of it goes into Telephony → "Trunks and connections" → "Add provider".

The data was collected on 9 September 2026 from carrier websites, the regulator's numbering plan and published PBX vendor materials; links are in the "Sources" section.

In short#

  • You can buy a number with a SIP trunk in Denmark, and no licence is needed for it. Numbers are only assigned to companies that provide communications services professionally — the venue buys a number and a channel from such a carrier and never deals with the registers itself.
  • The main local pitfall: large carriers sell the trunk bundled with their own access line, not "over the internet". At TDC Erhverv the signalling and media travel through an MPLS VPN on TDC Fibre or DSL; at Telenor the access is built "bypassing the internet" and terminates in their own router at the customer site. Our PBX lives in the cloud and has no line of its own in a Danish office — those trunks simply cannot reach it.
  • The easiest carrier to connect is Redspot. It is the only one on the market that publishes a ready-made Asterisk configuration: host voice.redspot.dk, the G.711 a-law codec, RFC 2833 DTMF, registration with a number and a password. It is bought self-service in their web shop, and Copenhagen numbers are in stock.
  • The second candidate is Uni-tel through its partner 1TEL (sip3.1tel.dk): a Danish carrier with a Danish contract and invoice, the trunk is registration-based too, delivery "from one day to the next" on working days. Some parameters have to be asked for — their guide is written for 3CX.
  • Danish numbers are eight digits long and have no area codes, while the PBX matches a line by the last seven digits. Two Danish numbers share that tail more often than you would expect — check it before you add a second line.
  • The country's codec is G.711 a-law, required or recommended by every local carrier. Our PBX speaks G.711 and G.722, so there will be no transcoding; nobody in Denmark pushes G.729.
  • Almost everyone asks for a CVR (the Danish company registration number) and a contract with a legal entity. Redspot is the exception: paying in the shop is enough.

Numbers in Denmark#

  • The country code is +45. The international prefix is 00 and nothing else; Denmark has no national prefix (no leading zero).
  • The length is 8 digits and there are no area codes. Leading digits 2–9 are reserved for eight-digit numbers; digits 0–1 are taken by short service numbers. Inside the country you dial all 8 digits, and the form 00 45 <number> is also allowed for a domestic call.
  • You cannot tell a mobile number from a fixed one by its prefix. The numbering plan only splits ranges into "mainly mobile" and "mainly fixed", the "fixed" ranges contain a long list of mobile exceptions, and numbers have been portable between carriers since 2008.
  • Service ranges: 801–809 — free for the caller, 901–905 — premium-rate information services, 909 — the carrier's own premium rate, 116xxx — harmonised social services, 112 — the emergency number, and range 37 — twelve-digit numbers for devices (M2M).
  • The format the number arrives in. Nobody states it publicly: even Redspot only says that the number arrives in the address part of the call in full. Ask for the format (+45… or 8 digits) when ordering and match it with what is written on the "Lines" tab.

On the "Lines" tab the number can be entered in any form: the PBX matches the last seven digits. For Denmark that means the first digit of the eight-digit number is dropped:

The lines 32 96 00 46 and 42 96 00 46 are indistinguishable to the PBX — they share the tail 2960046. In countries with area codes such a clash is close to impossible; in Denmark it is routine, because the number is not tied to geography and ranges are handed out in blocks of 1,000 and 10,000 to carriers all over the country. Before you buy a second and a third number, compare the last seven digits.

Who sells a number with a SIP trunk#

Provider Which numbers Trunk for your own PBX Mode How to order Note
Redspot Danish local numbers (Copenhagen 32/33/35/36/38/39 in stock), numbers of other countries yes, with a published Asterisk configuration REGISTER self-service web shop the only one in the country with public parameters; 4/8/16/32/64 concurrent call tiers
Uni-tel (via 1TEL) Danish fixed and mobile yes, the trunk is provisioned by Uni-tel REGISTER, sip3.1tel.dk order form through 1TEL, CVR required 3CX Preferred Provider for Denmark; 10 lines by default
Dstny A/S Danish fixed numbers and ranges yes, "with and without QoS" stated in the contract sales department, a 3-month trial exists the only large carrier that names Asterisk and FreePBX in an official document
ipnordic A/S Danish ranges are ported to them yes, "keep your own PBX", connected over the internet stated in the contract sales department, CVR required no limit on the number of channels
Maxtel.dk fixed and mobile yes stated in the contract request by phone or form the most transparent price list: trunk from DKK 99/month, number DKK 5
plusTEL / siptrunk.dk Danish numbers, DID ranges yes, "directly or as part of your phone system" stated in the contract contact form, phone built on Asterisk/FreePBX themselves; DID at DKK 4 per number
Firstcom Europe Danish yes, over the ordinary internet stated in the contract sales department ⚠️ an encrypted variant is sold separately and will not work for us
Norlys (formerly Telia Danmark) fixed ranges of up to 10,000 numbers yes, from 10 channels stated in the contract business sales first question: does the trunk work without their access line?
3Business (Hi3G) fixed and mobile yes, bundled with their own phone system stated in the contract business sales ask whether the trunk connects to a PBX outside their ecosystem
GlobalConnect Danish, Nordic yes stated in the contract corporate sales usually sold together with their fibre
Telavox Danish, through the Bandwidth aggregator nominally yes stated in the contract Telavox DK sales Asterisk is not on their list of supported PBXs
TDC Erhverv (Nuuday) fixed, DDI ranges 1…10,000 yes, but only on top of their own TDC Fibre/DSL line with QoS both (dynamic or static registration) sales department, legal entities only cannot reach a cloud PBX
Telenor Danmark fixed, DDI yes, but only through their Nordic Connect access and their router at your site not documented account manager cannot reach a cloud PBX
Flexfone Danish no — only the "numbers plus their own PBX" bundle — — a number here is worth porting away
DIDWW, Telnyx, Twilio, Zadarma Danish local, mobile, toll-free yes REGISTER or by IP online, with document checks see "International providers"

Full cards go to the first two: only they have published a server address and an authorization mode. For the other Danish carriers the parameters come with the contract — they have a section of their own.

Redspot#

A shop-style IP telephony carrier (the legal entity is Redspot Limited) selling SIP trunks in several countries, Denmark among them. It is the only player on the Danish market that publishes a ready-made Asterisk configuration — not "contact our sales department", but the whole settings block.

Ordering is self-service: pick a SIP trunk subscription and a number in the web shop (the basket shows free Copenhagen numbers +45 32…, 33…, 35…, 36…, 38…, 39…), pay, and receive a letter with the number and the password. The concurrent call tiers are 4, 8, 16, 32 and 64, adding DKK 12 / 35 / 80 / 148 / 273 to the subscription; porting a number costs DKK 148.

What to enter in the admin panel

Field Value
SIP host voice.redspot.dk
Port 5060
Transport UDP
Registration ✅ REGISTER — "Register with the provider"
Login your phone number (it is also the trunk user name)
Password the password from the welcome letter

What to set up on the provider's side: buy a subscription and a number (or order a port) → choose the concurrent call tier → save the number and password from the letter → if you take a number range, ask in which format the number arrives → on your side let the voice traffic through (UDP 10000–20000) and allow exchange with their addresses 34.255.42.177 and 13.49.205.52.

Pitfalls ⚠️ Their configuration allows a single codec, G.711 a-law; that costs us nothing, as a-law is first on our list too. The guide is written for the old Asterisk engine, so none of its lines is copied literally — our form needs only the six fields from the table above (the "Outbound proxy" field, which Redspot requires to stay empty, simply does not exist here). Redspot Limited is not a Danish legal entity: the contract, invoices and support are in English and Danish, and they describe their own Asterisk support as limited.

Source: Asterisk, TrixBox o.l. — opsætningsvejledning · Generel opsætningsvejledning · SIP Trunks Danmark — 09.09.2026.

Uni-tel via 1TEL#

Uni-tel A/S is an independent Danish carrier founded in 2008, unique in delivering over both the TDC and the Telenor network; it has passed the 3CX interop test. Its SIP trunks are sold and documented by its partner 1TEL ApS (part of JED ApS, Odense) — on the 3CX list for Denmark it appears as a Preferred Provider.

The order goes through 1TEL ("SIP Oprettelses Bilag"); the trunk is delivered "from one day to the next" on working days, Uni-tel issues the invoice, and the contract has no lock-in period. The trunk includes 10 concurrent lines by default.

What to enter in the admin panel

Field Value
SIP host sip3.1tel.dk
Port 5060 — the usual value; the 1TEL guide does not print the port, so confirm it when ordering
Transport UDP — according to 3CX data as of 09.09.2026, encrypted transport (TLS) is disabled in the Danish templates; confirm when ordering
Registration ✅ REGISTER — the trunk is registration-based
Login the trunk number in international format (+45…)
Password the "SIP Trunk Password" from the provisioning form

What to set up on the provider's side: fill in and send the "SIP Oprettelses Bilag" (a business service, CVR required) → order the number of concurrent lines you need → get new numbers from the carrier's range or submit a porting form for your existing ones → ask support whether they need the static IP address of our PBX (the 3CX guide only mentions registration).

Pitfalls ⚠️ The guide is written for 3CX and relies on its built-in template for Denmark: some values (port, transport, the form of the presented number) are baked into that template and never printed on the page — you will have to get them from support. The chain of responsibility is split in two: the technology and the invoice come from Uni-tel, the sale and the instructions from 1TEL. And a separate note on porting: a mistake in the form means the losing carrier rejects it and the retry costs DKK 150 for the main number and DKK 50 for each additional one.

Source: Opsæt 1TEL SIP Trunk på 3CX · Uni-tel — IP-telefoni · 3CX — SIP Trunk Providers, Denmark — 09.09.2026.

Contract-only carriers#

These carriers do offer a trunk for a third-party PBX, but they publish no parameters: the host, the port and the authorization mode arrive with the contract or in the go-live email. There is no "What to enter" table here — ask the account manager for the parameters using the list in "What to ask the provider" and enter them in the same form as for everybody else.

Dstny A/S#

A large Danish carrier from Nærum. It is the only one in the country that lists the supported third-party PBXs by name in its official product sheet — and the list includes Asterisk and FreePBX (along with 3CX, Avaya, Cisco Call Manager, Alcatel, FreeSWITCH and others). The trunk is sold in two variants — with and without a quality-of-service guarantee on the line; we need the second one, which is what "over the ordinary internet" means. The channel count is practically unlimited, and there is a three-month trial for DKK 3,000 excluding VAT (up to 10 channels and 10 Danish numbers).

From their published requirements for the customer PBX: at least 100 kb per channel, the G.711 a-law and µ-law codecs, support for the SIP standard (RFC 3261), DTMF (RFC 2833), RTP (RFC 3550) and caller identity (RFC 3325). The customer installs and configures their own PBX themselves.

The first question for the account manager is whether the caller identity header (RFC 3325, P-Asserted-Identity) is mandatory on outgoing calls: our PBX does not send it by default, and if Dstny requires it, the setting has to be agreed with our support in advance. Then the usual list: host, port, transport, authorization mode, login and password, the format of the incoming number, and an explicit "a trunk without the quality-of-service line, the PBX is in the cloud with a static IP".

ipnordic, Maxtel, plusTEL, Firstcom, Norlys, 3Business, GlobalConnect, Telavox — what is known
  • ipnordic A/S — a carrier from Gråsten, strong among clinics and law firms. The product is described exactly the way we need it: "keep your existing PBX", connected "simply over the internet", no limit on channels, existing ranges ported to them. No parameters published. ⚠️ "Your existing PBX" usually means a box in the customer's office for Danish carriers — confirm in writing that yours is in the cloud.
  • Maxtel.dk ApS — a small carrier from Skanderborg with the most transparent price list in the country: a SIP trunk from DKK 99/month excluding VAT, DKK 5 per fixed and mobile number, a "trunk plus SMS" bundle from DKK 299/month, fax over SIP included, channels adjustable both ways. They configure the trunk themselves. Their main scenario is their own platform, with a third-party PBX as a side case.
  • plusTEL / siptrunk.dk — a carrier operating since 2007 (both domains lead to the same site). The trunk is "numbers, lines and traffic", usable directly or as part of your own office telephony; DID costs DKK 4 per number. They build on Asterisk and FreePBX themselves, so you will find a common language faster than with the incumbent.
  • Firstcom Europe — a UCaaS carrier with offices in Albertslund, Aalborg and Aarhus. They do have an ordinary internet trunk to a SIP-compatible customer PBX, but an encrypted variant is also actively sold — do not take that one, see the next section.
  • Norlys — the former Telia Danmark: the deal closed in April 2024 and the Telia brand was finally retired on 05.05.2025, so old "Telia DK SIP Trunk" instructions no longer lead anywhere. What is public: a minimum of 10 channels, ranges from 1 to 10,000 numbers, porting of fixed and ISDN numbers, their own channel management interface. The emphasis on "high quality of service" hints at the same access dependency — ask about it first.
  • 3Business (Hi3G Denmark) — "a bridge between fixed, mobile and IP telephony", sold together with their own office telephony. The carrier is a mobile one and fixed voice is an add-on for it: the chances of getting clear SIP parameters for a third-party Asterisk are lower than with the first two.
  • GlobalConnect A/S — the largest alternative owner of fibre and data centres in Denmark. The trunk is in their portfolio, but the product targets customers who already have their fibre — the same access dependency as TDC and Telenor is likely.
  • Telavox — a Swedish UCaaS with a Danish presence. A trunk is offered, but the list of supported PBXs is Mitel, Avaya, Aastra and LG-Ericsson, with no Asterisk on it; Danish numbers come through the Voxbone aggregator (now Bandwidth). With such carriers "not on the supported list" usually means "it may work, but the ticket will be closed as not supported".

Which trunks will not work with our PBX#

  • TDC Erhverv (Nuuday). The trunk exists, the modes are documented (both registration and address-based authorization) and the recommended codec is G.711 a-law. But it is delivered over an MPLS VPN on a TDC Fibre or DSL line, and having that line is an explicit condition of the contract. There is no public internet in the picture, so a cloud PBX has nothing to connect to. The workaround — keeping your own gateway in the office and building a second trunk from it to us — means separate hardware, a second point of failure and a second line on the invoice.
  • Telenor Danmark. Protocol-wise everything is ours: SIP over UDP, G.711 a-law with a 20 ms frame. But the access is built "directly between the customer and Telenor, bypassing the internet", and the trunk terminates in a Telenor router installed at the customer site and connected by cable. For a cloud PBX that is a full stop; dismantling their equipment on termination is at the customer's expense.
  • Firstcom SIP Encrypt and any "TLS/SRTP only" variants. Our PBX supports UDP and TCP on trunks and has no encrypted trunk transport — see "Network and compatibility". Order the ordinary trunk.
  • Flexfone. They do not sell a trunk for a third-party PBX at all and say so on their own page: numbers and the PBX come as one package. A venue already on Flexfone has to be moved by porting the number, not by "adding a trunk".
  • Telavox. Asterisk is not on their list of supported PBXs, and a "Danish number" here is a number of a third-party aggregator.
  • Norlys and GlobalConnect are not a "no" but an "unknown": both promote the product together with a quality-of-service guarantee. Make that your first question to the account manager: "do you sell the trunk without your access line, to our public IP address?"

International providers with Danish numbers#

Every large international provider sells Danish numbers; their trunk parameters are the same for all countries — take them from the provider's card in the admin catalogue or from "Add provider". Here is only what is specific to Denmark:

  • DIDWW — local, national, mobile and toll-free Danish numbers, local termination with guaranteed caller ID and access to emergency services. The modes are a static endpoint (by IP) and dynamic registration, and both suit us.
  • Telnyx — Danish local numbers from $3/month, porting of Danish numbers available. Denmark is on their list of countries where filling in the document package is mandatory at order time.
  • Twilio — local, mobile and toll-free numbers are available, but the address has to be Danish: a company registration document showing a Danish address, or a Danish ID with an address for a private person. Their trunk cannot register, only authorize by IP — so you will need the static IP of the dedicated PBX (the "Server" tab).
  • Zadarma — Danish virtual numbers are available; the documents asked for are a copy of an identity document (both sides) and a current address. Their Danish market partner is plusTEL.
  • Certified by 3CX for Denmark — 1TEL, Colt, Telxi and Twilio. For us that is an indirect but useful marker: those four definitely hand the trunk out to a third-party PBX.
  • Bandwidth (formerly Voxbone) is present in Denmark at wholesale — its numbers are what Telavox resells. Colt sells a Danish SIP trunk at carrier level: excessive for a single venue.

Number porting#

  • Porting takes one working day — that is a regulatory requirement. The clock starts when the losing carrier receives the request; the gaining carrier must activate the subscription and the number within that period, and a delay entitles you to reasonable compensation.
  • The gaining carrier files the request. You do not have to write to your previous carrier: the port happens once the new contract takes effect, and it also terminates the old one.
  • The details must match to the letter. 1TEL warns about this explicitly: a mistake in the porting form means the losing carrier rejects it and the retry costs DKK 150 for the main number and DKK 50 for each additional one. Check the company name, address and contract number against the documents, not from memory.
  • A number range belongs to the carrier, not to the venue. Numbers in Denmark are not assigned to end users, and transferring ranges between carriers requires the regulator's approval. "My number" means "the number I use under a contract": when you leave, you port it, you do not take it with you.
  • Porting fees differ by carrier — at Redspot, for instance, it is DKK 148.
  • Update the venue address in the new provider's portal after the port: emergency calls to 112 are routed by the address recorded with the carrier.
  • Mobile numbers are portable too, but a mobile number is riskier in our setup because of the seven-digit tail — check for collisions.

Rules and paperwork#

The regulator, numbers, presented number, emergency calls, call recording
  • There is no licence for IP telephony. The rules are set by the telecommunications act and the numbering plan (BEK nr 1883 of 07.12.2020). Numbers and ranges are distributed among those who provide communications services professionally and are not assigned to end users, large customers included; ranges are handed out in blocks of 1,000, 10,000 or 100,000. A venue gets a number only through a carrier.
  • Where carriers apply. The numbering plan itself was issued by the Danish Energy Agency and names it as the administrator of numbers throughout, but the telecom section is run today by the Agency for Digital Government (digst.dk/tele) — that is where applications for numbers and codes are filed. None of this concerns the venue: the carrier files them.
  • The presented number. There is no direct "only your own numbers" ban in the numbering plan, and the market confirms it: Redspot openly offers keeping your incoming calls on the old trunk while sending outgoing calls through them and still presenting your own local numbers; 3CX marks Danish partners as supporting that mode. The carrier's contract, however, usually keeps a clause that you may only present numbers you legitimately hold — so in the "Present as" rule use the numbers of your own contract.
  • Spoofed Danish caller IDs are not blocked yet, and that is a deliberate pause: carriers can see that a call presenting a Danish number comes from abroad but, by their own public explanations, are not allowed to correlate subscriber location data for that purpose; the industry is looking for a common solution. Even so, building a venue's telephony on presenting somebody else's Danish number is a bad idea.
  • Emergency calls to 112. The number may only be used for its purpose, and the carrier's location lookup is based on the installation address; if the customer's internal network covers several addresses, the customer has to supply the location data. Once the venue moves, update the address in the portal, or the emergency service will drive to the old one.
  • Call recording. There is no special telecom rule: European data protection law and the Danish supervisory authority apply. The practice is the same as in the rest of the EU — an announcement at the start of the call; in the admin panel it is switched on in the location settings.
  • Paperwork. With Danish carriers the service is almost always for legal entities: a CVR and a contract are required. International providers replace the CVR with their own document checks, which can be stricter — Twilio, for example, requires a Danish address and a company registration document, which for a foreign owner may take longer than a contract with a Danish carrier.

If it does not work#

Symptom Danish cause What to do
The Redspot trunk does not register even though the login and password are correct Their traffic comes from 34.255.42.177 and 13.49.205.52, and the exchange with those addresses is blocked Allow UDP exchange with those addresses in both directions and test the link again
The carrier asks to install their router at your site or to buy a line with a quality guarantee That is the TDC Erhverv and Telenor scheme: the trunk arrives over their own line Such a trunk cannot reach a cloud PBX — choose another carrier
The carrier offers an encrypted trunk and the link never comes up The trunk is set on TLS/SRTP (at Firstcom that is a separate product) Ask for the ordinary UDP trunk: we have no encrypted transport on trunks
The call lands on the wrong line Two Danish numbers share the last seven digits Compare the tails and split the clashing numbers between different trunks
The line is not matched at all The provider sends the number in a different format than the one recorded on "Lines" Confirm the format with the carrier and adjust the line entry — see "Add a number"
Outgoing calls are rejected with a caller identity error The carrier requires the RFC 3325 header (P-Asserted-Identity); Dstny lists it in its requirements Write to our support: the header is added on the PBX side, there is no such field in the trunk form
The call connects but the audio is one-way The voice traffic (UDP 10000–20000) is not allowed through, or the carrier offers an unexpected codec Check the network and insist on G.711 a-law — it is the de facto Danish standard
The trunk went silent after the server was moved The carrier's allow list still holds the previous IP address of the PBX Warn the carrier about a move in advance and ask them to update the address

Causes that do not depend on the country are in "If calls do not go through"; checking the address and the port is in "Test the link".

Frequently asked questions#

Which carrier should I choose if nothing is connected yet?#

Redspot, if speed matters most: purchase in the web shop without negotiations, Copenhagen numbers in stock, and every parameter known in advance because they publish it themselves. Uni-tel via 1TEL, if a Danish contract, a Danish invoice and local support matter more: that trunk is registration-based too and is delivered from one day to the next on working days, but the port and the transport have to be confirmed with support.

Why can I not take a trunk from TDC or Telenor — they are the largest carriers?#

Because they sell the trunk together with their own access line: at TDC the signalling and voice travel through an MPLS VPN on their fibre or DSL, at Telenor over a separate channel bypassing the internet, with their router in your office. Our PBX sits in the cloud and has nothing to physically connect to that line with. It is not about the protocol — the SIP itself is exactly what we need in both cases.

Do I need a Danish company and a CVR?#

With Danish carriers, almost always yes: the trunk is sold to legal entities under a contract, and the provisioning form asks for a CVR. Redspot is the exception here — paying in the shop is enough. International providers replace the CVR with their own document checks, and those can be stricter: Twilio, for instance, requires a Danish address and a company registration document.

Why do my two Danish numbers behave as one?#

Because the PBX tells lines apart by the last seven digits, while a Danish number is eight digits long and has no area code. The numbers 32 96 00 46 and 42 96 00 46 share the tail, so the call will land on whichever line is found first. Compare the last seven digits before adding a second line; if they clash, the numbers have to be split between different trunks.

The venue already has a number with Flexfone — can a trunk be added to it?#

No: Flexfone only sells numbers together with its own PBX and says itself that connecting its trunks to an external system is not needed. The only way is to port the number to a carrier that does sell trunks (Redspot, Uni-tel via 1TEL or Dstny). By law the port takes one working day.

Sources#

All links checked on 09.09.2026.

Regulator and law

Carriers

PBX vendor certifications and international providers

Documentation
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