According to the BNF grammar in the RFC (3261) the host part of a SIP URI should not contain underscores ('_'). However, pjsip does accept it. >>> lib <pjsua.Lib instance at 0x7fc4750277e8> >>> lib.verify_sip_url("SIp:alice:mypassword at invalid_hostpart.com:5070;param=xxx") 0 I'm using pjsip version 1.0.3 BTW. PS: This is the BNF grammar for SIP URIs :) SIP-URI = "sip:" [ userinfo ] hostport uri-parameters [ headers ] hostport = host [ ":" port ] host = hostname / IPv4address / IPv6reference hostname = *( domainlabel "." ) toplabel [ "." ] domainlabel = alphanum / alphanum *( alphanum / "-" ) alphanum toplabel = ALPHA / ALPHA *( alphanum / "-" ) alphanum alphanum = ALPHA / DIGIT -- Sa?l -- "Nunca subestimes el ancho de banda de un cami?n lleno de disketes." ---------------------------------------------------------------- http://www.saghul.net/