2 Servers - Missed call notifications

HI,

We have 2 Servers with a IAX trunk between them - both running 13.0.190.19

We can make calls between the two quite easily and the 2nd server uses the 1st to make outgoing calls as only this server has a SIP trunk.

The only issue we have is that although calls between the users of server A and Server B to users on the same server will leave a missed call notification if the call is not answered - missed calls between users of different servers do not - so user on A calls user on B - missed call = no missed call notifciation.

I’ve played around with the dial plan options (set to Ttr on the trunk) but not got anywhere.

Has anyone else seen this? have any advice?