[OpenSIPS-Users] Fwd: Retransmission and 300 Redirect

Răzvan Crainea razvan at opensips.org
Thu Oct 22 13:41:29 EST 2020

Hi, Pavel!

I think you can play with the T1 and T2 timers[1] to avoid, or at least 
control better the re transmissions, however note that these settings 
affect all transactions, not just the INVITE transaction one you're 
targeting. TBH, I wouldn't do that.

Another possibility would be to completely avoid re-transmissions is to 
go stateless (instead of using t_relay(), just use send() and the 
generic onreply_route).

However, the best way to achieve this, is to fix the redirect_server to 
be able to either send a 100 Trying within a reasonable time, or at 
least be able to absorb re-transmissions.

In order to make sure you're only processing a single 300 Redirect, you 
can use a flag that says whether the redirect was processed or not, and 
only reprocess it if the flag is not set.

[1] https://opensips.org/docs/modules/3.1.x/tm.html#param_T1_timer

Best regards,

Răzvan Crainea
OpenSIPS Core Developer

On 10/22/20 12:32 PM, Pavel Eremin wrote:
> Hi, community!
> Is anyone can help me to understand how to avoid 2 situations:
> 1. I don't want to send retransmission  (INVITE) from "opensips" to 
> "redirect" server, even "redirect" does not answer.
> 2. If I have sent a few invites to "redirect" , then i will receive a 
> few 300 Redirect messages, and "opensips" will generate branches for all 
> contacts in all "300 Redirect" messages. how can i ignore all "300 
> Redirects".
> I am not sure that t_check_trans() can help me with that.
> Thanks. I added a picture with the call flow I have.
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