Cisco CME not calling out

[fov]

Has anyone had any experiance of Cisco CME not connecting calls to an ISDN channel?
I have a system where users are calling but it is never making outside the router but only every few calls.

[fov]

Got to the bottom of this in the end. Another provider had tried to take over the ISDN and had enabled CPS (carrier pre select) only because the transfer of the ISDN hadnot worked the CPS was not working and so no calls were working.