Hi Team I think, I might have found something that was overseen in the rtpengine module. A (ipv6) <=> rtpengine <=> B (ipv4) Invite+SDP from B to A It looks like this works as expected. A SDP c= line is created containing an ipv6 address. Invite, no SDP from A to B Reply with SDP offer from B to A The information about A being reachable via ipv6 and therefore an ipv6 c= line being required, could be taken from the via header of the reply. But am I right to fear, that the rtpengine module does not do this at the moment? Mit freundlichen Grüssen -Benoît Panizzon- -- I m p r o W a r e A G - Leiter Commerce Kunden ______________________________________________________ Zurlindenstrasse 29 Tel +41 61 826 93 00 CH-4133 Pratteln Fax +41 61 826 93 01 Schweiz Web http://www.imp.ch ______________________________________________________