It seems that each carrier has its own weirdness to overcome. To start with you should turn on sip tracing to see what they are sending you and if some other field contains the destination number. In the FreeSWITCH console type: Sofia global siptrace on And enjoy the data that spews forth as you place each test call J That's how I figured out how CallCentric was sending calls to my FS installation so I had to modify my inbound dialplan to look for a different field than the vanilla configuration looks for, but that's to be expected. It's also possible, or even likely, that Mondotalk is expecting you to send the destination number in a different field, but I have no good suggestions on that. Bote From: Bill Ross Sent: Saturday, 02 May, 2015 14:08 Subject: [Freeswitch-users] MondoTalk trunk configuration Hi; I have two freeswitch installations each with a free mondotalk number as gateway. Attempting to get them to communicate extension to extension via these gateways. The originating extension sends a proper invite (destination # is 8757469): INVITE sip:8757469@192.168.1.1 SIP/2.0 Freeswitch, in forwarding invite through mondotalk gateway sends this: INVITE sip:@sip99.mondotalk.com SIP/2.0 Which lacks the destination # and is rejected. Clearly, I have messed up in my mondotalk dialplan. Any hints as to what I am missing? Thanks; Bill