CX v20 Forwarding Calls – Need Help!

[haba-beton]

Hello everyone,

I’m running 3CX v20 with multiple SIP trunks and many extensions. Here’s the setup:

TRUNK 1
• DID +1 111 111 111 → Extension 1000
TRUNK 2
• DID +2 222 222 222 → Extension 2000

We manage all call forwarding through the 3CX Web Client rather than on our SNOM phones. Extension 2000 uses an “Away” forwarding profile that routes both internal and external calls to an external number.

The Problem​

1. Extension 1000 (TRUNK 1) calls Extension 2000.
2. Extension 2000 is on “Away” and forwards every call to +3 333 333 333.
3. On the SNOM phone, I see “vorübergehend nicht verfügbar” (“temporarily unavailable”).

If I change the internal forwarding number on Extension 2000 to 000333333333 (so our outbound rules strip the leading zeros and convert it to +333333333), the call appears in the SIP trace—but it’s sent out via the wrong trunk. Specifically, the call to +333333333 from +1 111 111 111 is attempted over TRUNK 2 , which fails because TRUNK 2 doesn’t recognize the +1 … DID.

What I’ve Tried​

• Forwarding to an E.164 number directly (+333333333) results in “temporarily unavailable.”
• Forwarding to a dial plan number (000333333333) correctly rewrites to +333333333, but still uses the wrong trunk.

Can anyone advise how to force the forwarded call out of TRUNK 1 (the trunk that owns the +1 … DID) instead of TRUNK 2?
Thanks in advance for your help!

Sadin Junuzovic

 

[NicholasP_3CX]

This might be the E164 settings of the PBX in action and modifying the number.



Disable this. Since you are using your outbound rules for the nmbe rprocessing you do not need the PBX to override any E164 settings.

 

[haba-beton]

@NicholasP_3CX Thank you for the suggestion. I’ve disabled the E.164 settings as you advised, but I’m still seeing the wrong trunk being used: it’s trying to place the call out via trunk-2 while using the caller ID (number) from trunk-1, and of course that fails. Any idea what might still be forcing it onto the wrong trunk?

 

[YiannisH_3CX]

Can you send us a screenshot of your outbound rules? Most probably the call is forwarded through the wrong outbound rule as it is the first that matches so Trunk 2 is used instead of Trunk 1.
Forwarded calls are still using outbound rules so make sure those are in the correct order.

 

[haba-beton]

 

[haba-beton]

Okay, now I’ll give you the real example without placeholders:

Extension 1620 on trunk “TEI” has a forwarding rule that sends internal calls to its external phone number. When I dial 1620 from extension 1740 on trunk “GAR,” the call fails—and the SIP logs show it’s trying to place the call over trunk TEI using my caller ID from trunk GAR. However, if I call the external number for extension 1620 on TEI directly, the call succeeds.

 

[haba-beton]

Here are the outbound dialing rules:

• [PLACE]-1: Prefix 000 → converted to +
• [PLACE]-2: Prefix 00 → converted to +49
• [PLACE]-3: Prefix 0 → converted to +498634 (where 8634 is the local area code for that place)

 

[YiannisH_3CX]

First of all extensions do not "belong" to trunks. So if you forward a DID or trunk to an extension that does not mean the extension and trunk are bound.
So you dial 1620 from 1740 and 1620 forwards the call to an external number. Which group does 1620 belong to?

 

[haba-beton]

So you dial 1620 from 1740 and 1620 forwards the call to an external number.

Yes exactly. 1620 belongs to group "TEISING" and 1740 belongs to group "GARCHING"

 

[YiannisH_3CX]

So it's correct. 1620 makes the forward so the call will match the outbound rule of group "TEISING". And I am guessing you have originator call ID configured on your trunks so it shows the caller ID of extension 1740.

 

[haba-beton]

These are the Parameters and OrginatorCallerId is configured on FromUserPart and P-AssertedIdentityUserPart.
Thats I think the default on the template for telekom sip trunk.
Should I change the FromUserPart Paramter to something else?

 

[YiannisH_3CX]

Thats I think the default on the template for telekom sip trunk.

Just checked all Telekom templates (DE) and this is not the default configuration. I am not sure which Telekom product you are using but they usually use the PAI header for authentication.
If you are using a supported Telekom product, delete the trunk and recreate it using the default template and check.

 

[haba-beton]

Im using Telekom CompanyFlex Voice Data Template. I'll try to recreate it and I'll let you know. Thank you very much!

 

[haba-beton]

I tried it out with the template Telekom CompanyFlex Voice Data and it still doesnt work.

Also when I use that template, the Main Trunk Number is displayed on the Called User Screen.

 

[haba-beton]

@YiannisH_3CX – Quick update:

Everything is functioning now, except that when we place calls to Poland or Austria, the main trunk number is shown instead of the caller’s number. If I change the Outbound P-Asserted-Identity parameter from LineNumber to OriginatorCallerId, the correct number is displayed—but then call forwarding stops working. Do you have any ideas on how to resolve this?

 

[YiannisH_3CX]

Everything is functioning now, except that when we place calls to Poland or Austria, the main trunk number is shown instead of the caller’s number. If I change the Outbound P-Asserted-Identity parameter from LineNumber to OriginatorCallerId, the correct number is displayed—but then call forwarding stops working. Do you have any ideas on how to resolve this?

If the issue is only with Poland or Austria then probably Telekom is replacing them due to regulations. It's best to leave the default settings and speak with Telekom about the specific issue.

 

[haba-beton]

Okay, thank you very much for the help!