Guys, need some help here
setup an FreePBX for my hikvision intercom
the hikvision intercom does have a indoor screen with SIP cababilities
setup 2 SIP’s
So calling from a SIP client to hikvision, like 6003 to 6001 fails
Calling from hikvision from 6001 to 6003 works as expected! audi+ + video
PBX = 192.168.0.69
KH9310 = 192.168.0.71 - SIP 6001
Linphone desktop = 192.168.0.221 => SIP 6003
below are full logs?
what is wrong? 
<--- Reliably Transmitting (NAT) to 192.168.0.221:5060 --->
SIP/2.0 503 Service Unavailable
Via: SIP/2.0/UDP 192.168.0.221:5060;branch=z9hG4bK.st~Dkjsz6;received=192.168.0.221;rport=5060
From: "Vanessa" <sip:[email protected]>;tag=16fnOgl2o
To: sip:[email protected];tag=as3f6b972f
Call-ID: um0VkjSQKx
CSeq: 21 INVITE
Server: FPBX-15.0.16.81(17.7.0)
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH, MESSAGE
Supported: replaces, timer
X-Asterisk-HangupCause: Subscriber absent
X-Asterisk-HangupCauseCode: 20
Content-Length: 0