we run Grandstream GXP 1630 and GXP 2170 VoIP deskphones with our FreePBX 22.214.171.124.
We have issues with the call forwarding feature, which can be configured directly on the deskphones, e.g. using the phone’s menu or by key combination *72targetTelephoneNumber# . The call forwarding icon will be displayed on the deskphone’s display then but incoming calls will not ring on the c.f. target device.
The issue only occurs when target number is external. This means:
- Caller internal - callee internal - fwd target internal: WORKS!
- Caller external - callee internal - fwd target internal: WORKS!
- Caller internal - callee internal - fwd target external: FAILS!
- Caller external - callee internal - fwd target external: FAILS!
I tracked it down by SIP traces to the DIVERSION header being misconfigured. For successful authentication our provider Vodafone expects this form:
where: +49 is country code Germany / 211 is city pre-selection / 4567 is company’s block / 654 is callee’s extension.
The diversion header I can see in the failed c.f. sip traces looks like this:
where: 654 is callee’s extension / 192.168.1.101 is deskphone’s IP address
It is sure that the first mentioned diversion header is correct. I got it from the sip trace of a successful call diversion which was configured directly on the FreePBX using the Misc destinations function.
The question is now: How to rewrite the false diversion header being submitted by the deskphone?
Has anybody an idea?
Thanks in advance!