Please let me know what you find out. MyContacts starts phone calls using telepathy directly (not the common nokia dbus signal) and that is the only difference I can imagine from placing a call with the regular contacts or phone application.

On a new release I plan to offer the option to use the nokia dbus instead of telepathy because telepathy will not automatically handle "#" or "*" on the phone number according to a previous post on this thread. You may have found another reason.... please keep me posted.