Line number: which of your numbers was called

What a line number is#

A business often has several numbers on one provider wire (SIP trunk): "bookings" and "delivery", the numbers of two locations, a toll-free and a local number. The line number is the one of your numbers the customer called. It is not the caller's number: the customer's number does not change, and call-backs go to it.

If the provider passes the number somewhere other than where the PBX looks for it, all numbers of the trunk look the same to the PBX: a call to "delivery" goes wherever a call to "bookings" goes. This article explains how to set this up and check it.

What you need to get started#

How the PBX identifies the line number#

The number is identified once, as the call comes in, by the "trunk + number" pair:

1. The PBX takes the number from the place set for the trunk (Request-URI by default, as it always was).
2. It normalises it to international format (+7…). A number in the 8… form or without the area code is recognised too.
3. It matches it against the line numbers of this trunk.

An unrecognised call never goes as "the trunk's first number" — only along the trunk's own route.

Step 1. See what the provider sends#

1. Open "Calls" → the PBX call log → the card of an incoming call on the trunk you need.
2. Go to the "SIP" tab (the call has the "SIP packets available" badge).
3. At the top is "Key facts from the headers": which number was called. For MANGO the numbers come from Diversion — its Request-URI and To carry only the account name, for example "inbound".
4. Below are the packets. Click INVITE: the headers open as a "name · value · what it means" table.
5. Find where your number is: Request-URI, To, P-Called-Party-ID, Diversion (first or last) or the provider's own header. Choose that place for the trunk in step 2.

Step 2. Choose where to take the number from#

The provider window: Telephony → "Phone providers" → the provider window → "Settings" tab → "Where the provider puts the line number" block, field "Line number is in".

"Header name" — Latin letters, digits, "-" and "_", starting with a letter (for Zadarma, for example, CALLED_DID). Service headers such as To, Via, Diversion and X-Cenaly-… are not accepted.

"Provider profile" for the "Automatic" option:

The hint in the window. If the trunk has an incoming call with a SIP capture, the window looks at the last one itself:

• "The number +7… (name) is found in Diversion — top. Choose it?" — the "Choose" button sets that place;
• "as set now" — the number is already where the setting points;
• "Only account logins were in the packet, no line number" — the provider did not pass the number at all.

A number that is already a line of another trunk of the location is not suggested.

What is known about providers#

The information comes from the provider catalogue and the providers' own documentation; if your case is missing or does not match, look at the "SIP" tab of the first incoming call (step 1).

Step 3. Sort out new numbers#

A number the provider sent a call to, but which is not among the trunk's lines, can be found by the PBX itself. The trunk's "New numbers" block:

An "incoming only" number takes part in incoming calls only: it is not used for outgoing calls, the caller ID, registration or number checks.

Not discovered: the account login, numbers shorter than 6 digits and a number already added on another trunk of the location.

The "Lines" tab#

The "Lines" tab of the provider window is a "Number · Name · Last incoming · Route" table with the "incoming only", "Detected " and "off" marks.

"Ignore" on a number that is already added removes it from the lines, and the PBX will not add it again. The same marks show in the trunk's list of numbers on the "Phone providers" tab, under the number's row.

Step 4. Set the number's route#

The "Number route" window opens from the "Lines" tab and from the "⋯" menu of a number's row:

• "As the trunk: <where the trunk's calls go>" — the number has no rules of its own (its own rules are turned off; one click brings them back);
• "Own route" — the action is chosen right there: an employee, a ring group, a voice menu, voicemail, the AI secretary, an external number, hang up.

"Call path now" shows which rules will fire: an override, the number's own rule, a trunk rule or a location rule. The order of checks:

1. shared override rules;
2. the number's own rules;
3. the trunk's rules;
4. the location's shared rules;
5. the location mode.

An own route is available only in the "as trunk / own" route model. The owner turns it on in the "Route model “as trunk / own”" block of the same window after a preview: how many rules will change and what needs to be set by hand. It can be rolled back there too. Complex distribution (round-robin, a greeting with text) is edited under "Incoming call path".

Where the line number is shown#

Limitations#

• Works only on a dedicated PBX after the firmware update. Without it: the provider window says "Not available on this PBX — update the PBX firmware" (calls are identified by the Request-URI), the new-numbers block says "This PBX does not report new numbers yet — update the PBX firmware", the route window says "A number's own route is not available on this PBX".
• If the provider passes the line number in no header at all, numbers of one trunk cannot be told apart.
• Up to 100 discovered numbers per trunk. The PBX reports a new number at most once every 10 minutes per number and at most 10 new numbers an hour per trunk.
• A number's own route — only in the "as trunk / own" route model.
• An "incoming only" number cannot be used for outgoing calls, the caller ID, registration or number checks.

Troubleshooting#

FAQ#

Does the caller's number change too?#

No. The line number is your number that was called. The customer's number stays the same, and call-backs go to it.

Why doesn't an unrecognised call go as "the trunk's first number"?#

So that a call to one number is not routed by mistake as another one. An unrecognised call follows the trunk's route.

A new number was added by itself — will it make outgoing calls?#

No. A discovered number is added as an "incoming only" line: incoming calls only, the trunk's route.

Can one number have its own menu while the others share one?#

Yes: "Own route" on that number, "As the trunk" on the others. This needs the "as trunk / own" route model.

Related sections#

• Telephony: your own PBX
• Checking your PBX's incoming numbers
• Connecting a provider's number to the PBX
• Calls: recordings and speech analytics