Problem resolved -- thank you for pointing me in the right direction. Was following a Cisco application guide for router configuration, which specified the following voice service voip command:  signaling forward unconditional.  This enabled SIP GTD. Following command disabled SIP GTD and corrected issue for me:  signaling forward none. Thanks again. --- On Tue, 12/28/10, Joel Mange <telconettech@yahoo.com> wrote: From: Joel Mange <telconettech@yahoo.com> Subject: event i_media_error 988 Incomplete offer/answer To: freeswitch-users@lists.freeswitch.org Date: Tuesday, December 28, 2010, 7:35 PM Hello.  New to FS and in need of help. Environment is as follows: Linksys SPA-962 (x94140) <---> FS <---sip---> Cisco3845 <---qsig---> TDM PBX <--> TDM phone (x91237) Can complete call from TDM phone to Linksys SPA-962.  Can't complete call from Linksys to TDM phone:  TDM phone rings, but call fails when it goes off-hook.  Getting the following sofia error:  nua(0x8b60cf0): event i_media_error 988 Incomplete offer/answer. I think the above message tells me that the other side of the call sent an invalid SDP.  Having trouble identifying the invalid SDP and making necessary correction. Siptrace and router running-config at:  http://pastebin.freeswitch.org/14896 Any help appreciated.