[asterisk-users] pjsip: Inbound calls: selecting the correct trunk with one provider and different numbers

Michael Maier m1278468 at mailbox.org
Thu Jun 8 15:22:23 CDT 2017

Hello Joshua,

thank you very much for your extremely quick answer! I really appreciate
your work and your friendly and your patient support!

On 06/07/2017 at 10:33 PM, Joshua Colp wrote:
> On Wed, Jun 7, 2017, at 05:28 PM, Michael Maier wrote:
>> Hello!
>> I've got a problem to select the correct trunk if there is one provider
>> and different numbers with different configurations for this same
>> provider.
>> Example:
>> trunk-prov1-2345
>> trunk-prov1-2346
>> trunk-prov1-2347
>> Each trunk registers an own number (at the same provider) and provides
>> own configuration: they have different allowed codecs e.g..
>> What I'm experiencing now, is, that each incoming call is provided by
>> trunk-prov1-2346, no matter which number has been dialed.
>> The problem isn't the routing (this is done on base of the correct DID),
>> but the problem is, that wrong codices are used if the wrong trunk is
>> selected.
>> Is this a problem of asterisk or is it caused by the provider, which
>> always addresses the same "trunk" regardless which number has been
>> called?
> Asterisk is the one who associates an incoming message with an endpoint.
> In the case of providers you can use IP based matching - which would
> behave as you see, only one can be matched. The second option is the
> line option[1] which may or may not work (it depends on the behavior of
> the provider). If it works then the right endpoint would be chosen. Out
> of those two options there's nothing else applicable built in to match.
> [1]
> http://blogs.asterisk.org/2016/01/27/the-pjsip-outbound-registration-line-option/

Unfortunately Deutsche Telekom doesn't support this solution :-(. I
tried it by faking DNS entries and use different server names to get
different IP addresses. Unfortunately, this doesn't work, because the
name wasn't accepted by the ISP. Using the IP address directly isn't a
good solution, too, because you can't receive changes any more.

A "solution" would be via regularly created rpz DNS entries, which are
used to resolve a fake server name (like fake1.real.name.com) by
asterisk to the desired IP. All other string operations would use the

Ok, it's a pipe dream!


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