[asterisk-users] How to ignore REFER entirely with chan_sip or PJSIP ?

[Daniel Tryba]

On Fri, Jun 15, 2018 at 05:32:30PM +0200, Olivier wrote:
> In my testing, I saw that Asterisk always included a REFER value in each
> INVITE's Allow header, no matter how allowtransfer/allow_tranfer was set.
> 
> Is there a way to remove this REFER value entirely either globally or
> specifically for a given peer/endpoint ?

No, not with asterisk itself.

> Which telephony feature would loose without REFER method ?

AFAIK none except the ability to REFER (obviously).

What you can do is:
-route calls via a proxy that gives you the ability to modify SIP on
the fly (e.g. kamailio)
-wihh chan_sip use disallowed_methods (= REFER)
-with pjsip reject a REFER in the dialplan:
 https://wiki.asterisk.org/wiki/display/AST/res_pjsip+Remote+Attended+Transfers

The last 2 options will make PBXs/endpoints that use REFERs, since
asterisk is advertising it, fail in certain scenarios. So cleanest is
the first option, which will take some work redesigning your setup but
might be a good thing on the long run.