bsnl wings works well on gxp 1625 when configured,but not working when add as sip trunk on ucm 6204.When dialled it say all lines are busy.Can anyone Help?
what connection do you use?
What firewall do you use?
did you correctly create the in and out rules on trunk in UCM?
Disabled SIP ALG?
Did you create the NAT rules correctly in ACL?