[Serusers] SER & pdt module & problem with rfc

Hi, I've always got my problem with pdt, moreover I don't know if my ser.cfg is correct or if the other SIP accept my requests. For iptel.org it refuses relaying : 403 No relaying :-( For fwd.pulver.com 483 Too Many Hops :'( And I've found something : When I use a GrandStream phone the INVITE request contain this : Via: SIP/2.0/UDP XX.XX.95.40;branch=z9hG4bK6e3e.beff4bf6.0 Via: SIP/2.0/UDP YY.YY.114.221;rport=62261;received=ZZ.ZZ.78.42 And fwd.pulver.com says 483 But when I use Linphone : Via: SIP/2.0/UDP XX.XX.XX.XX:5082; branch=PPC1805202.z9hG4bK05a4,SIP/2.0/UDP 192.246.69.223;branch=z9hG4bK05a4.14d79b55.1,SIP/2.0/UDP 193.56.114.19:5060;received=81.250.78.42 But on SIP's rfc, GrandStream use the right syntax but not linphone and pulver ? Is there a mistake of my part ? The two expressions are correct ? Thanks you for listenning to me. Greetings, Charles