Fairly easy question I assume ut I need to know why adding an external phone number would would stop outbound calls. It is an H323 gateway with a PRI, 4 digit DNs (6000-6999) and when we add 716422XXXX the users can not make outbound calls. Any ideas are appreciated.
No additional dial peer required. If you are only changing the mask, it is almost certainly being blocked by the carrier. Try "debug isdn q931" and look at the diconnect cause code. The following link should help.