Hoosier

I like Express Talk a lot, but I'm having trouble using Express Talk Basic Free Version 3.06 with my SIPPhone.com account. The first problem is that when I try to dial a number like 1-747-474-3246 (SIPPhone's echo test line) the call won't go through (I get a recording, "Your call cannot be connected as dialed") unless I remove the hyphens. If I remove the hyphens and dial 17474743246, I get connected to the echo test line and hear the greeting, but do not hear any echo (i.e. the echo test fails). If I call the same provider (SIPphone.com) with the same account using another user agent (X-Lite, for example), the call goes through (even with hyphens in the number) and the echo test works fine. Apparently, there's something about Express Talk that SIPPhone.com doesn't like. Any ideas? Thanks in advance for any assistance.