We can reach all destinations with ringback, just German Telekom does not trigger ringback.
This is what I tried:
- setting “r” in Dial to outbound trunk: no change, ringback missing.
- setting “R” in Dial to outbound trunk: wrong syntax.
- calling “Ringing()” before Dial: very short ring, then silence.
Asterisk version is 13.18.2.
German Telekom is known for problems like this but we need to solve this on our side.
We tried the “Ringing()”-approach again on our test installation and it worked.
The change will be applied this evening on out prod infrastructure and we will test.
We noticed that “Ringing()” only works for some devices, not all.
There is always a short ring, some phones-models then play ringback, some do not.