Another thing to try is create a SIPBroker Alias for
userID@webcalldirect.com
It will assign you something like xxxxxxx (i believe it is 7 digits) which can then be called as *011xxxxxxx@sipbroker.com
Sign Up at SipBroker for this, the rest is pretty self explanatory.... about how to go about creating an Alias
Note: You don't normally need to sign up for anything unless in cases like this when a numeric alias may simplify things