SIP Server does not send sdp on reinvite

[tech]

Hello All,

Although the option reuse-sdp-on-reinvite=true on extension and trunk, when the call comes from Trunk1 and transferred to another number via Trunk2, there is no sdp attached to invite message coming after RequestSingleStepTransfer. Is there another option for trunk to use? Since two trunks are different, I could not use Refer.

Thank you for your help.

[tech]

Also make-call-rfc3725-flow = 1 for Trunk 2, but there is no sdp on invite sent to Trunk 2.

Thank you.

[hsujdik]

Try removing the reuse-sdp-on-reinvite on the extensions. It should be true for only one party of the call leg

[tech]

I tried deleting the option on extension but it did not solved the problem. No sdp message, gateway returns SIP message 500 Body-less INVITE is not supported.

Thank you.

[hsujdik]

Ah, btw, make-call-rfc3725-flow=1 should be on the extensions, not the trunk if I remember correctly

[jamesmurphyau]

reuse-sdp-on-reinvite=false on trunk 1
reuse-sdp-on-reinvite=true on trunk 2

[tech]

I made a change and now I'm using the same trunk for incoming call and the transfer call. There is no SDP body again. Is there any other options for call transfers and SDP?

Thank you.

[jamesmurphyau]

I'm going through this same pain at the moment.. a carrier doesn't support empty sdp.. we've created another trunk with a prefix "ext/" (uses same IP as inbound trunk).. agents are told to use this when transferring externally.. another option if you have WDE is use the intercommunication setup and use a routing strategy to customise the transfer after the agent does it (adding the custom prefix to select the other trunk)