Netherlands: SIP providers and connecting a number to the PBX

This page continues the general guide on connecting a provider's number to the PBX: that page covers what is the same for any operator — the two trunk modes, what to ask the provider, what to enter in the form, network requirements and the connectivity check. Here is the Dutch specifics: who in the country sells a number with a SIP trunk, what that operator issues and what of it to enter in Telephony → "Trunks and connections" → "Add provider".

The data was collected on 9 September 2026 from operator documentation, the regulator's materials (ACM) and the national numbering plan (Nummerplan telefoon- en ISDN-diensten); links are in the "Sources" section.

In short#

• You can buy a number with a SIP trunk in the Netherlands, and this market is one of the most convenient. A venue needs no licence and no permit: instead of a licence the country has a notification (mededeling) to ACM, and it is filed by the operator you buy connectivity from, not by you.
• Almost every notable operator works in registration mode (REGISTER) over UDP or TCP with the G.711a and G.722 codecs — exactly what our PBX speaks. There is no operator here whose trunk is TLS-only.
• If you have not picked an operator yet, take Voys: it is the only one that published the full set of trunk parameters, down to keep-alive and IP ranges, and its preferred codecs (G711a, G722) match ours exactly. The price is €23.50 one-off plus €4.75/month for two lines. Fallbacks are CheapConnect (no subscription fee at all) and Business-ISP (the clearest firewall instructions).
• The main local pitfall is the port. The VoIPGRID platform (Voys, VoIP Telecom) registers new trunks on port 6060, not on the usual 5060. This is the most frequent cause of "not registering".
• The second pitfall is showing your own number on outgoing calls. Voys expects the number in the Remote-Party-ID header, SpeakUp in P-Asserted-Identity with Privacy: id; our PBX does not send these headers, so the call goes out with the trunk's default number.
• A geographic number is tied not to where the PBX stands, but to the subscriber's registered address. If you have no address in the required region, take a non-geographic 085 or 088 number — they need no address binding, and for a cloud PBX this is the cleanest option.

Numbers in the country#

• Country code — +31. A geographic number is exactly 10 digits, counting the leading 0. Hence two shapes: 0 + a two-digit area code (netnummer) + 7 digits (020 1234567 — Amsterdam, 010 — Rotterdam, 070 — The Hague, 030, 040, 050) and 0 + a three-digit area code + 6 digits (0512 123456).
• Mobile numbers — 06 + 8 digits (the same 10 digits in total).
• Non-geographic ranges: 085 — general communications service numbers, 10 digits; 088 — corporate numbers, 10 digits (issued in blocks of 100 by the regulator itself); 084/087 — personal; 0800 — free for the caller; 0900/0906/0909 — premium information numbers; 0970/067 — machine-to-machine.
• Dialling: inside the country — 0 + area code + number, abroad — 00 + country code, emergency — 112 with no code.

On the "Lines" tab a number may be entered in any form: the PBX compares the last seven digits. ⚠️ In areas with a two-digit area code the subscriber part is exactly 7 digits, so numbers from different areas (020 1234567 and 010 1234567) can collide on that tail. If your numbers come from different cities, check the routing of every line by hand — "Add a number and routing".

Who issues a number with a SIP trunk#

The first six rows are operators whose server address and mode are known in advance: their cards are below. The next eight issue trunk parameters only after a contract — they have a separate section. Why KPN, Vodafone, Odido and Digihero will not work is further down.

Voys#

An operator from Groningen running its own VoIPGRID platform (it works in the Netherlands, Belgium, Germany, Spain, France, Portugal, Austria and South Africa). It sells both a cloud PBX and a "VoIP-trunk" for an external system: 2 lines — €23.50 one-off and €4.75/month, every extra line — €11.55 one-off and €2.40/month; lines are activated and cancelled by the day, the minimum is two. The operator states upfront that it helps connect the trunk but does not support configuring the PBX itself.

What to enter in the admin panel

What to set up at the provider: portal → "Voip Trunk" → create a trunk (description, "Aantal lijnen" — the number of simultaneous calls, "Intern nummer" — a three-digit identifier) → enable "Gebruik de Caller ID informatie van de trunk" so that the PBX picks the number → set the allowed destinations in "Belbevoegdheden" → in "Geavanceerde (SIP) instellingen" set CLI header = Remote-Party-ID (the operator asks for this on every Asterisk-based system) → point the numbers at the trunk.

Pitfalls ⚠️ Port 6060 on new trunks is the most frequent cause of "not registering". The operator asks to leave STUN and Outbound Proxy empty: filled in, they break connectivity. Our PBX does not send Remote-Party-ID, so the "Show as" rule will not work at Voys — the trunk's default number will be shown; the workaround is to make the number you need the trunk's default in the portal. The incoming number arrives with a plus (+31501234567), while your own number on outgoing calls is expected in national form (0501234567). Automatic fraud protection disables the whole trunk on suspicious traffic, not a single call. If you filter traffic by address, allow their networks 195.35.114.0/24, 195.35.115.0/24, 185.103.76.0/22. Source: VoIP-trunk: Mijn eigen PBX instellen, SIP-instellingen, pricing — 09.09.2026.

VoIP Telecom#

An operator on the same VoIPGRID platform as Voys — with the same rules and the same set of fields. Its server address is not shared: every brand on the platform has its own, and it is issued together with the trunk.

What to enter in the admin panel

What to set up at the provider: order a trunk → take the server address, Account ID and password from the portal → point the numbers at the trunk → check that the incoming number format is "full number with a plus".

Pitfalls ⚠️ The platform's preferred codecs are G711a and G722, so our whole set passes. Keep-alive is 10 seconds and needs no changing. As with Voys: the incoming number carries a plus, the outgoing CLI is national; STUN and Outbound Proxy are left empty. The platform addresses for the firewall are the same: 195.35.114.0/24, 195.35.115.0/24, 185.103.76.0/22. Source: Algemene trunkdetails — 09.09.2026.

CheapConnect#

A Dutch operator focused on cheap minutes. There is no subscription fee at all: the account is free, incoming calls are free, billing is per second with no connection charge; outgoing calls to landlines cost €0.0238/min and to mobiles €0.0500/min. The operator does not cap the number of simultaneous calls.

What to enter in the admin panel

What to set up at the provider: create a free account → top up the balance → create a trunk and take its login and password → attach the purchased number to the trunk for incoming calls → if needed, set the number shown on outgoing calls.

Pitfalls ⚠️ The model is prepaid: once the balance runs out outgoing calls stop while incoming ones keep working. G.729 comes first in their codec list and we do not have it — negotiation has to fall through to G.711a/G.722, so check this on the very first call. The configuration example published by the operator is written for the old Asterisk mechanism and does not apply to our PBX as a whole — only the address, login and password are needed from it. The operator also asks that the system does not identify itself as asterisk: that name is reserved on their platform, and if registration is refused it is worth mentioning to their support. Source: Handleiding Asterisk / FreePBX, SIP Trunk — 09.09.2026.

Business-ISP#

A Dutch business provider (internet and telephony) with a public knowledge base where the trunk parameters are published in full — including the addresses its platform calls from.

What to enter in the admin panel

What to set up at the provider: order a SIP trunk → receive the login and password → point the numbers at the trunk → if you filter traffic by address, allow the four addresses of their platform (listed in the same knowledge base article).

Pitfalls ⚠️ At this operator numbers everywhere carry the country code without a plus — 31201234567, 31612345678, 318001234; do not add a plus in the outgoing rules. Tone dialling is RFC 2833, same as ours. Their media port range is 6000–20000, wider than ours; nothing needs changing on our side, but the venue's firewall (if it is involved at all) must pass that traffic. Source: Algemene instellingen SIP trunk — 09.09.2026.

MaxiTEL Telecom#

A business operator — telephony, internet access, M2M — with a detailed public knowledge base of settings.

What to enter in the admin panel

What to set up at the provider: MaxiTEL portal → create a SIP account (trunk) → take the Account ID and password → point the numbers at it → disable the voicemail notification subscription (MWI): the operator asks not to use it, otherwise equipment "spams" their platform.

Pitfalls ⚠️ The operator has no separate SIP proxy: the Proxy and Outbound Proxy fields are left empty or repeat the same ha.mtsip.nl; STUN is left empty, the platform detects NAT itself. The operator's preferred codec is G.729, which we do not have: negotiation has to fall through to G.711a, and their voicemail server converts G.722 into G.711a anyway. Tone dialling is RFC 2833 (in-band does not work on G.722 at all). The public instructions are written for desk phones — the operator has no separate page about a trunk for an external PBX, so it is worth confirming the parameters with support when ordering. Source: Best Practice instellingen VoIP — 09.09.2026.

SpeakUp (Enreach)#

An operator from Enschede, part of the Enreach group; its "Speakup SIP-Trunk" product is sold precisely as a way to connect an existing PBX. The operator does not publish its own parameters — the table below holds what was published in third-party platform profiles as of 09.09.2026; confirm them when ordering.

What to enter in the admin panel

What to set up at the provider: order the "Speakup SIP-Trunk" → receive the UserID, UserName and UserPassword → point the numbers at the trunk → agree the number format (the operator uses the country code without a plus, 31123456789).

Pitfalls ⚠️ The operator reads your outgoing number only from the P-Asserted-Identity header together with Privacy: id, and our PBX does not send it — the call will go out with the trunk's default number. Presenting numbers that are not in your contract is not allowed in the Netherlands, and the operator's profile states this separately. The codecs are G.711a, G.711µ and G.729; the first two are ours. Source: Speakup SIP-Trunk, the Enreach/Swyx profile — 09.09.2026.

Operators that issue parameters under contract#

At these operators a trunk for an external PBX is a regular product, but the server address, login and password appear only in the customer portal or in the contract. The list of questions worth asking the account manager before signing is in "What to ask the provider".

• Callvoip — a Groningen provider whose outward trunk is described as a regular scenario, with Asterisk named explicitly among the supported systems; it recommends a trunk "from 10 numbers upwards". Parameters are issued together with the trunk account in the "Mijn Callvoip" portal. ⚠️ On their side there is an IP allow list filled in by the customer (enter the static IP of your PBX from the "Server" tab), a cap on simultaneous calls and spending limits — €10 / €25 / €50 per hour, day and week by default: "calls stopped" here is often a limit rather than a fault.
• VOIPZeker — a large cloud telephony provider; it has both a "SIP-trunk koppelingen" help section and a dedicated article about connecting Asterisk, but that article is served only from the customer portal. Ask for it together with the credentials.
• KeenSystems — an independent operator whose trunk template is built into 3CX and Yeastar; because of that the public instructions never print the host — it comes from the template. For our PBX the parameters have to be requested from support. A useful detail: the operator gives customers a registration and SIP message log, handy when troubleshooting.
• Dstny Nederland — a large operator (formerly Voiceworks/Destiny), sales by quote only. ⚠️ The E.164 format has to be requested explicitly when ordering the trunk, otherwise the incoming number arrives in a different form and the line may not match it. The profile has no signalling encryption — which does not bother us.
• Pocos (Sewan) — an operator from Venlo, certified by Unify and 3CX. It issues a main number with a block of extensions (+31773020190 and onwards), a username of the form sip175964, a password and a channel count written firmly into the contract: "no ringing after the Nth call" is that contractual limit.
• basicVoice (WinCOM) — the budget "SIP Trunk Unlimited" plan at €6/month: one number in the plan (or porting your own), free incoming calls, monthly cancellation, no cap on simultaneous calls. Compatibility with Asterisk is stated explicitly. ⚠️ Parameters are published not as text but as a ready configuration file for 3CX — for our PBX ask support to send them in plain text.
• VoiceOne — a reseller, "SIP Trunk" from €6.50/month with number porting; the mode and server address are confirmed when ordering.
• Hallo — an IT provider with a "SIP-trunk" product; parameters and mode are confirmed when ordering.

Who will not work#

• KPN. The incumbent has two different products, and both miss. The consumer "Vast Bellen" does publish SIP parameters, but the login is issued by a service tool that works only from the KPN line itself and without a VPN, and only one device can be registered in the KPN exchange — a cloud PBX is not what this scenario is built for. The business "SIP Trunk" product is managed: it connects a system at the customer's premises through a KPN gateway. One more nuance: SIP OPTIONS probes are disabled at KPN, so the "Check connection" button may stay silent even on a working trunk.
• Odido (formerly T-Mobile NL) — does not issue SIP credentials to subscribers at all and sells only its own cloud telephony.
• Vodafone Business NL — the One Net and One Fixed products do include a trunk, but connecting an external system goes through a session border controller (yours or the operator's) and a PBX certification programme; Asterisk is not listed among the publicly certified systems. If this operator is already yours, ask about certification as the first question.
• Digihero (formerly Belcentrale) — the Belcentrale brand no longer exists on its own: the company was bought in 2020 and has traded as Digihero since December 2020, and there is no public "trunk for an external PBX" product on the site.
• XS4ALL — the brand is closed, sales ended on 24.12.2021 and customers were moved to KPN. The address sip.xs4all.nl, which still shows up in old instructions, does not work.

International providers with Dutch numbers#

Dutch numbers are sold by DIDWW, Telnyx, Twilio, Plivo, didlogic, Vonage, Bandwidth, Sinch, Infobip, Zadarma, Sonetel, AVOXI, Freezvon and others. This is the default path if the company is registered outside the Netherlands or if you need numbers in several countries at once.

• The Netherlands is a standard point of presence. At didlogic, for example, the Dutch node (sip.nl.didlogic.net) comes first in the list of regions, so for a European PBX it is also the closest server.
• A geographic number still requires a local address. The regional binding runs through the subscriber's registered address, and at international providers it is framed as "proof of local address or business registration". The legal and cheap way around it is an 085 or 088 number: they are non-geographic and require no address binding.
• Only your own number may be presented on outgoing calls. Number spoofing is prohibited in the country, and from 10.07.2026 to 25.09.2026 the ministry of economic affairs is consulting on a numbering bill, one block of which is a restriction on using Dutch numbers outside the country. As of 09.09.2026 this is still a draft; if you take a number from an international provider for the long run, its fate is worth following.
• Emergency calls at international providers are a separate service, and more often there is none at all: 112 needs a local operator or an explicitly ordered Emergency service.
• The modes differ. Cards for Zadarma, Telnyx and Twilio are already in the catalogue when adding a provider — the server address and mode are filled in for you.

Number porting#

• The right to port is set by law (art. 4.10 and 4.11 of the Telecommunications Act, Telecommunicatiewet). You may claim number retention before and without terminating the contract with the old operator, and if the port fails the old operator must reactivate the number. Supervision is with ACM.
• The request goes to the new operator — the one you are moving to. At online operators (basicVoice, VoiceOne) it is simply a "Nummerbehoud" checkbox during the order; they agree the porting date so that the number switches over in a single day.
• 085 and 088 numbers can be ported too. But an 088 block issued to a company by the regulator itself follows its own rules: you may only use it yourself and may not hand it out to customers.
• Geographic numbers and moving house. The number is tied to the region through the subscriber's address: changing your registered address to another region makes the old geographic number questionable. For a venue that may relocate, 085 is safer.
• Sole traders (ZZP) are served on equal terms with companies; there is no separate barrier, documents are requested by the operator as needed.

Rules and documents#

If it does not work#

1. "Not registered with the provider" at Voys or VoIP Telecom. First check the port: new trunks on this platform register on 6060, not on 5060. Second, check whether STUN and Outbound Proxy are filled in: at Voys and MaxiTEL they must be left empty, filled in they break registration.
2. The password looks right, but there is no registration. At every operator described here the trunk's SIP password differs from the customer portal password. At CheapConnect the login is the phone number itself, not the account email.
3. The wrong number is shown on outgoing calls. Voys reads the number from the Remote-Party-ID header, SpeakUp from P-Asserted-Identity with Privacy: id; our PBX sends neither. There is one workaround: make the number you need the trunk's default number in the operator's portal.
4. Outgoing calls are rejected. Check the format: at Business-ISP, SpeakUp, Dstny and Pocos the number carries the country code without a plus (31…), while on the VoIPGRID platform your own number is presented in national form (0501234567) even though the incoming number arrives with a plus. The format is adjusted with prefixes in the rules on the "Outgoing" tab.
5. The call connects but there is silence. The codecs did not negotiate: at CheapConnect, MaxiTEL and SpeakUp G.729 comes first in the list and our PBX does not have it. Ask the operator to enable G.711a or G.722 — requirements for the provider.
6. Incoming calls arrive but the line is not matched. At Dstny the E.164 format must be ordered explicitly; without it the number arrives in a different form. The second case is a collision of the last seven digits between numbers from different regions (020 1234567 and 010 1234567): separate such lines by hand or take numbers from one region.
7. Calls suddenly stop while registration is fine. At Callvoip spending limits (€10 / €25 / €50 per hour, day, week) and an IP allow list are on by default — changing the PBX address silently breaks the trunk. At Voys suspicious traffic disables the whole trunk through automatic fraud protection.
8. The "Check connection" button is silent while the trunk works. At KPN SIP OPTIONS probes are disabled; MaxiTEL recommends a 30-second keep-alive instead. At these operators no answer to the probe is not a verdict.
9. The address was taken from an old instruction. sip.xs4all.nl (the brand is closed) and sip.sipnl.net from a 2010 technical note are dead addresses. Take the address from your own operator's portal.

Causes that do not depend on the country are in "If calls do not go through"; the SIP trace in the trunk menu is described there too. Checking the address and port — "Check connection".

Frequently asked questions#

Which operator should I pick if nothing is connected yet?#

Voys. It is the only operator in the country that published the full set of trunk parameters, its preferred codecs match ours, and lines are activated and cancelled by the day. Fallbacks are CheapConnect (no subscription fee at all, you pay only for minutes) and Business-ISP (clear instructions and published platform addresses for the firewall).

Can I get a Dutch number if the company is registered outside the Netherlands?#

A geographic one is hard: it is tied to a region through the subscriber's registered address, and the operator verifies that binding. There are two practical routes: take a non-geographic 085 number (it needs no address binding) or buy a Dutch number from an international provider — it will ask for documents too, but its procedure for foreign companies is documented.

Why are 085 and 088 better than a geographic number for a cloud PBX?#

They are not tied to a region: there is no address to prove and nothing to lose if the venue relocates. 085 numbers are sold by operators, while an 088 block is obtained by a company directly from the regulator — but may only be used by that company. A geographic number is worth taking when it matters that guests see their own city code.

Why does KPN not fit?#

The consumer "Vast Bellen" issues the SIP login through a tool that works only from the KPN line itself and without a VPN, and allows one device per account. The business "SIP Trunk" product is managed and connects a system at the customer's premises through the operator's gateway. Neither is designed for a PBX in the cloud.

How many channels (simultaneous calls) does a venue need?#

Usually 2–3: one is busy with a guest, the second with a courier or a supplier. At Voys the minimum is two lines with per-day expansion, at CheapConnect and basicVoice the number of calls is not capped, at Pocos it is written firmly into the contract. Ask about it before signing.

Sources#

All links verified on 09.09.2026.

Operators

• Voys — VoIP trunk: configuring your own PBX: https://help.voys.nl/voip-trunk-configuratie
• Voys — SIP settings (ports 5060/6060, codecs, DTMF): https://help.voys.nl/sip-instellingen-voip-telefonie
• Voys — SIP trunks: pricing and lines: https://www.voys.nl/voip/sip-trunks/
• VoIP Telecom — general trunk parameters: https://help.voiptelecom.nl/index.php?title=Algemene_trunkdetails
• CheapConnect — Asterisk/FreePBX manual: https://www.cheapconnect.nl/hulp/manuals/?getmanual=1067
• CheapConnect — SIP Trunk: codecs and pricing: https://www.cheapconnect.nl/en/sip-trunk/
• Business-ISP — general SIP trunk settings: https://faq.business-isp.nl/index.php?solution_id=1440
• MaxiTEL — best practice VoIP settings: https://maxitel.nl/documentatie/kennisbank/best-practice-voip/
• SpeakUp — Speakup SIP-Trunk: https://speakup.nl/telefonie/trunk/
• Enreach/Swyx — SpeakUp (NL) provider profile: https://service.swyx.net/hc/en-gb/articles/360010409039-SIP-Provider-SpeakUp-NL
• Callvoip — SIP trunk manual (channels, allow list, limits): https://www.callvoip.nl/ondersteuning/extra-features/sip-trunk-handleiding/
• VOIPZeker — integration with Asterisk: https://voipzeker.nl/helpdesk/handleidingen/sip-trunk-koppelingen/integratie-met-asterisk
• KeenSystems — connection guide (3CX): https://www.3cx.nl/blog/docs/voip-provider-nederland-keensystems/
• Dstny Nederland — SIP Trunk via VoIP: https://www.dstny.nl/sip-trunk
• Pocos (Sewan) — SIP trunks: https://pocos.nl/telefonie/sip-trunks
• basicVoice — SIP Trunk Unlimited: https://www.basicvoice.nl/sip-trunk/
• VoiceOne — SIP Trunk: https://voiceone.nl/voip/sip-trunk/
• Hallo — SIP-trunk: https://hallo.eu/producten/zakelijke-telefonie/sip-trunk/
• KPN — Vast Bellen specification (PDF, 27.01.2022): https://assets.ctfassets.net/zuadwp3l2xby/6BxqvsxmGtPqxiihrRY8S6/7643e21cf68d92c6187c66534ff9edb8/20220163_KPN_VastBellen_Specificaties_v20220127.pdf
• Vodafone Business NL — One Fixed: https://www.vodafone.nl/zakelijk/grootzakelijk/producten/one-fixed
• Odido — SIP credentials are not issued to subscribers: https://community.odido.nl/vast-bellen-494/sip-gegevens-odido-358323

Regulator and law

• ACM — registration of telecom providers: https://www.acm.nl/nl/telecom/telefonie-internet-tv-aanbieden/registratie-telecomaanbieders
• ACM — telephone numbers: https://www.acm.nl/nl/onderwerpen/telecommunicatie/telefoonnummers
• ACM — how to obtain an 088 number: https://www.acm.nl/nl/telefoonnummers/088-bedrijfsnummers-aanvragen
• ACM — number porting (art. 4.10 and 4.11): https://www.acm.nl/nl/telecom/zakelijk-abonnement-voor-bellen-en-internet/nummerbehoud
• ACM — policy rule on the availability of 112: https://www.acm.nl/nl/publicaties/acm-stelt-beleidsregel-vast-voor-mobiel-bellen-naar-alarmnummer-112
• Numbering plan for telephone and ISDN services (number length, the 085/088/0800/0900 ranges): https://wetten.overheid.nl/BWBR0010198/
• Ministry of Economic Affairs — consultation on the numbering bill (10.07–25.09.2026): https://www.internetconsultatie.nl/nummers/b1

Related pages#

• Connecting a provider's number to the PBX — general steps, trunk modes, network, connectivity check.
• Setting up SIP phones — how to connect desk phones and DECT to extensions.