[Users] Internet Providers changing the SIP headers

Hi fellows. We are in trouble with this "deceitful" error. I mean, errors. Look at RURI. Our proxy receive this "thing". We have a number there! Sometimes, this number is shown within the word REGISTER, like that: "REGI:34846:STER". We can rewrite the URI, but Openser doesnt understand the method "REGI:34846:STER". Second error: Via header. The REGISTER is showing the NAT_DEVICE_IP instead UA_IP. And this VoIP isnt behind any VoIP device! So, "who" are changing it? "Who" can does it? Is possible that some "device" between UA and our proxy change the headers intentionaly? This kind of problem had been happening some months ago and began at the same day to VoIPs were different regions of the country (Brazil). We would like to know with someone already has face it. Thank you all. Bruno Machado U NAT_DEVICE_IP:50764 -> PROXY_IP:5060 REGISTER :50764sip:proxy.com.br SIP/2.0 Via: SIP/2.0/UDP NAT_DEVICE_IP:50765;branch=z9hG4bK427600003ca00000 From: <sip:7011423@proxy.com.br>;tag=ab510000bf39ffff To: <sip:7011423@proxy.com.br> Contact: * Call-ID: 499effff9ff20000(a)192.168.1.5 CSeq: 100 REGISTER Expires: 0 User-Agent: Grandstream HT386 1.0.3.17 Max-Forwards: 70 Allow: INVITE,ACK,CANCEL,BYE,NOTIFY,REFER,OPTIONS,INFO,SUBSCRIBE Content-Length: 0 U PROXY_IP:5060 -> NAT_DEVICE_IP:50765 SIP/2.0 407 Proxy Authentication Required Via: SIP/2.0/UDP NAT_DEVICE_IP:50765;branch=z9hG4bK427600003ca00000 From: <sip:7011423@proxy.com.br>;tag=ab510000bf39ffff To: <sip:7011423@proxy.com.br>;tag=22aae43fbf528d3860ded8429db379db.546f..Call-ID: 499effff9ff20000(a)192.168.1.5 CSeq: 100 REGISTER Proxy-Authenticate: Digest realm="proxy.com.br", nonce="44edfeda1fe71fa609e7599bf2513e999e3741dd" Content-Length: 0 --------------------------------- Novidade no Yahoo! Mail: receba alertas de novas mensagens no seu celular. Registre seu aparelho agora!