Not sure if this info will help but our outgoing calls go from a Sipura SPA-841 phone through the Astrerisk’s TDM400P card and out to Verizon. Some phone numbers will not complete and other will. I am using Asterisk@Home 1.5. It would seem that this would controlled by outbound routing so I will post my outbound configuration:
NXXNXXXXXX
NXXXXXX
1NXXNXXXXXX
(and all the local prefixes here)
It inserts 3 waits (I believe these are 0.3-0.5 seconds each) before it starts dialing instead of picking up the trunk and immediately dialing. I needed it for my Verizon calls to work. Make sure that you’re puting it in the “Outgoing Dial Rules” section under “Trunks” and not the “Dial Patterns” section under “Outbound Routing”.