Hello

Please see below SIP Message

SIP/2.0 100 trying -- your call is important to us
Via: SIP/2.0/UDP 192.1681.101:5060;branch=z9hG4bK5a61798d7c850d39;rport=5060
From: <sip:summona@ 192.1681.101>;tag=51a0dc1e620de16d
To: <sip:101880171234567@ 192.1681.102>
Call-ID: 6fd9b9d563616c6c15f2d7fa@ 192.1681.101
CSeq: 21701 INVITE
Server: kamailio (5.1.9 (x86_64/linux))
Content-Length: 0

SIP/2.0 183 Session Progress
Via: SIP/2.0/UDP 192.1681.101:5060;rport=5060;branch=z9hG4bK5a61798d7c850d39
Record-Route: <sip: 192.1681.102;lr>
From: <sip:summona@ 192.1681.101>;tag=51a0dc1e620de16d
To: <sip:101880171234567 @ 192.1681.102>;tag=as728725b3
Call-ID: 6fd9b9d563616c6c15f2d7fa@ 192.1681.101
CSeq: 21701 INVITE
Server: VOS3000 V2.1.4.0
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH, MESSAGE
Supported: replaces, timer
Session-Expires: 600;refresher=uas
Contact: <sip:1018801751481417@104.216.39.66:5060>
Content-Type: application/sdp
Require: timer
Content-Length: 289
v=0
o=root 912643161 912643161 IN IP4 192.1681.104
s=VOS3000 V2.1.4.0
c=IN IP4 192.1681.104
t=0 0
m=audio 10784 RTP/AVP 18 101
a=rtpmap:18 G729/8000
a=fmtp:18 annexb=no
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=ptime:20
a=maxptime:230
a=sendrecv
a=nortpproxy:yes

2. I Want to hide the Contact Parameter and a= nortpproxy:yes ==> How to do it as well ? 

Thanks in advance.