Forwarded calls need to send Diversion Header according to regulations

[3c1b]

In Turkey VoIP service providers can only use their assigned DID numbers as CLI unless it is a diverted call. But if it is a diverted call the you must be sending diversion header to show this call is originated by the assigned account with the DID number if you want to send original callers CLI as second leg CLI.

Simple example is;
905321111111 (mobile number) calls 90312111111 a landline VoIP number working on 3CX. But in 3CX side theincoming call is forwarded to a mobile number which is 905322222222.

3CX makes an outbound call as the incoming call is forwarded to a mobile.
1- If no diversion header is available
a) You must be sending the 3cx sip trunk outbound DID
b) If you are sending incoming CLI as outgoing CLI the call will be dropped on vendor side as you cannot use another CLI then assigned to you.
2- If diversion header is sent in diverted/forwarded call to vendor.
a) If you are sendgin the incoming CLI as outgoing CLI with diversion like Diversion: <sip:[email protected]>;reason=unconditional the the call will pass to called mobile with the first leg CLI
As most ip pbx can do this 3CX cannot!

 

[NicholasP_3CX]

The Diversion header is activated in the forwarding rules of extensions when forwarding calls to a mobile or external number.
This option is available in the Away, Do Not Disturb and Custom 2 profiles.



From the 3CX Academy (Intermediate - Extension Profiles and Forwarding Rules)