Callcentric has done some checking and responded :
SIP/2.0 403 Forbidden
Call-ID:
22058063-3665323159-791333@msw1.telengy.net CSeq: 1 INVITE
Content-Length: 0
From: <sip:1281853xxxx@66.193.176.35>;tag=3665323159-791378
To: <sip:1281354xxxx@ss.callcentric.com>;tag=SP1bd5fabd58edbbd34
Via: SIP/2.0/UDP 204.11.192.170:5080;branch=z9hG4bK-69de6b04dab2bc878c0cbf25e1276e42;change=ta;received=204.11.192.170;rport=5080
Server: OBIHAI/OBi200-3.1.0.5110
Your OBi200 is rejecting the call with the 403 Forbidden.
I'm a newbie & have no idea where to locate "X_BlockedCallers"