[Serusers] Pb With Pstn-Gw

Hi I've a pstn Gateway with two network cards, so i have 2 ips on these pstn gw One Ip, is used only for sip signalisation (sig) the second ip is only used for media stream The problem is: in the sdp headers: the sig ip is located in " o= " field (ex:o=192.168.0.1 ) and the media ip is located in " c= " field (ex:c=192.168.0.2) It works with some ip Phones or SoftPhone (ex: Xlite) But Not all the phones seems to read th "c=" Field, so the phones don't receive the media streams Is There Way or Workaround for theses phones to work with Ser ? My Ser Config is the Onsip Config Thank you very Much Regards arno