Agent registering

    <send retrans="500">
        <![CDATA[
            REGISTER sip:[remote_ip]:[remote_port] SIP/2.0
            Via: SIP/2.0/[transport] [local_ip]:[local_port];branch=[branch]
            To: <sip:[service]@[remote_ip]:[remote_port]>
            From: agent <sip:[service]@[remote_ip]:[remote_port]>;tag=[pid]SIPpTag00[call_number]
            Contact: sip:[service]@[local_ip]:[local_port]
            Expires: 3600
            Call-ID: [call_id]
            CSeq: [cseq] REGISTER
            Max-Forwards: 70
            Content-Type: application/sdp
            Content-Length: [len]

            v=0
            o=0123456789 53655765 2353687637 IN IP[local_ip_type] [local_ip]
            s=agent
            c=IN IP[media_ip_type] [media_ip]
            t=0 0
            m=audio [media_port] RTP/AVP 8 101
            a=rtpmap:8 PCMA/8000
            a=rtpmap:101 telephone-event/8000
            a=fmtp:101 0-15
            a=ptime:300
            a=sendrecv
            a=sendrecv

        ]]>
    </send>

    <recv response="200"></recv>