[asterisk-users] Migrating asterisk 11 to 13: some callers get no ringback tone any more

Michael Maier m1278468 at allmail.net
Mon May 2 22:50:00 CDT 2016


I migrated asterisk 11 to 13 as user of FreePBX

As customer of German Telekom, I have three numbers and therefore three
trunks - each number is bound to one trunk.

After migration, some callers complained about missing ringback tone:
they didn't hear any ring tone and where surprised that they suddenly
got me anyway :-). The connection afterwards was as expected.

Deeper investigation yielded, that a few caller groups have been
affected by this problem:

- All POTS customers of German Telekom
- VoIP customer of T-Systems (usually companies which transfered their
  telephone system)

Not affected have been callers like All-IP customers of German Telekom
or any tested mobile caller or caller using other telecommunications

To make it even more strange: Calls coming from T-Systems customer via
call forwarding have been working fine, too.

The ringback tone wasn't missing, if the second number (the second
trunk) of the asterisk installation was used!

The only difference between those two trunks is: The first trunk is
configured to a ring group - the second trunk is configured directly to
an extension.

My solution after long time of digging around:
I added progressinband=never to sip_general_additional.conf

But this solution confuses me, because




Whenever ringing occurs, send "180 ringing" as long as "200 OK" has not
yet been sent. This is the default behaviour of Asterisk.

Why do I have to provide it especially if it is the default behavior?
Why did it work without this option with asterisk 11? Why is there
suddenly a difference in behavior between binding a trunk to a ring
group or an extension?

Michael Maier

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