Introducing SIP 200 delay

Hi , My Name is Ali . I am new to FS.

I’ve a special use case , where i need to Introduce a 1 sec delay on SIP 200 msg received from the B-Party, before forwarding it to the A-Party. My FS Installation is still intact , so any help would be appreciated.
Call Originated from
Terminator IP :



What exactly are you trying to solve with this delay?


Ive a route with 1 sec FAS after the IVR. Delaying the answer for 1 sec will fix the issue.

Can you elaborate?



The traffic comes from A party(Customr) to B party ( Route provider). The B-party terminates part of the calls with 1 sec duration due to wrong SIP 200 on SOME CALLs , so they are passed to the client as False Answer Supervision, causing a problem for sure. Thus, if i introduce a 1 sec answer delay on the SIP 200 between the provider (trunk) and the client , the 1 second calls won’t be registered as connected calls at the client side.

Below find some generic explanation of the fucntion from other switches:

Anti-FAS connection delay (milliseconds)
Specifies delay of connection signal (200 OK) for the anti-FAS call processing logic: when terminator connects the call, this signal is delivered to originator with delay. Should be greater than duration of connected FAS calls. FAS calls usually have short duration: 1-2 seconds. If we make a delay greater than the 1-2 seconds (let’s say 2500 milliseconds), the FAS calls will still be in “ringing” state at originator’s side, and not connected, so there will be no FAS at orignator’s side.

Thanks in advance,


Can you elaborate on what they are saying is wrong? Its best to fix something if its wrong vs trying to work around it. If you could tell me what they are saying about the 200Ok being wrong maybe I can give you better feedback.


HI Brian and thanks for you effort.

The fake IVR is played from the operator core , which im connected to thru a sip trunk. They confirmed thatthey are not able to solve the issue, as they play those IVRs for call centers and hotels.

Thus , i was looking for a work around. As you can see in the trace , The IVR comes with the SIP 180 and immediate SIP 200 after that. Thus introducing 1 second delay won’t register the call as connected on the calling party side.


Sounds like your provider is just broken, and needs to fix it.