The special characters that are defined in your remote coverage are used specifically for Data Call setup. The characters used for normal voice dialing are ~p, ~w, ~m, etc.
I found the information in my old Avaya Multi-Vantage Call Vectoring and EAS guide on page 459.
The Avaya web site doesn't have much in the support site regarding special characters, but it does have a little. Do a search on Avaya Support for "special characters".
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