On 24.05.19 at 13:14 Joshua C. Colp wrote:
> On Fri, May 24, 2019, at 6:02 AM, Michael Maier wrote:
>> Hello!
>>
>> some people are facing a problem regarding forbidden outbound calls to
>> the ISP. They start an outbound call, which is rejected by the
>> provider. Debugging revealed the reason: The IP used for the outbound
>> INVITE is different from the IP used for the REGISTER. That's why the
>> ISP forbids the outbound call.
>>
>>
>>
>> Background:
>>
>> A SRV lookup gives 3 hosts each with different priority. At the start
>> time, Asterisk takes the IP with the highest priority for the
>> REGISTER. REGISTER timeout is 660s.
>>
>> Some time later, lets say 300s, an outbound call is started, which is
>> rejected by ISP (forbidden), because of wrong destination (REGISTER IP
>> != INVITE IP).
>>
>> My question:
>> Is it possible, that asterisk performs a DNS lookup before it sends the
>> INVITE to the ISP for the outgoing call? At this moment, the DNS
>> reports changed priorities or the REGISTERed IP isn't there at all any
>> more and therefore, Asterisk uses another IP for the outgoing INVITE?
>
> Yes, this is how it works. The outbound registration and calling aren't
> associated at all. When an INVITE is done then another resolution occurs
> along with picking an IP address.
Unfortunately, this doesn't work, if the REGISTER to the existing old IP isn't
re-registered to the new IP before the INVITE is performed.
I forgot to mention one more difficulty: There is more than one number
registered to the same destination which may have differing
reREGISTER point of times.
Therefore, the process should be like this?
- Outbound call is started
- DNS lookup is performed
- Check for difference of REGISTER IP (of this dedicated outgoing number) and
INVITE IP
-> Difference detected? Yes:
-> Stop REGISTER for this number (or leave it if there is an ongoing
call using this
number)
-> Start REGISTER for this number with new IP
- Start INVITE to new IP
Thanks,
Michael
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