I don't see any reason why this shouldn't work. I would try another prefix mark first. If still no go, then I would open a ticket with the provider of your T1. The call is hitting the trunk but for some reason the trunk doesn't like it.

Valid enteries for prefix mark are 0 through 4.

Also try removing the area codein the NPA. I know I said to put it there, but try it without it as well.

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