Error when my asterisk is configured in "offline" mode

Hi all,

I have a problem with asterisk. My installations are always in offline mode.
With asterisk 13, I use webrtc2sip for browser call ( only chrome, because Firefox in this config not runs ). I can configure webrtc2sip config.xml file with my stun server and my dns server. All is ok.

Now I’ve upgraded Asterisk to version 15.4 and I use pjsip. If my system is online, all is ok (also Firefox, wow), but if I try to configure the system in offline mode ( like with webrtc2sip ), any calls runs. I don’t understand where I can configure my dns server.
In asterisk CLI, I have this log: ERROR[2783] pjproject: sip_inv.c …Error parsing/validating SDP body: Invalid SDP origin line (PJMEDIA_SDP_EINORIGIN)

Can Someone help me?

Thanks a lots.

Massimo Cimetti