Can not always make calls

I have a problem that I believe is a Bug in IPTel . Sometimes when I go to make a call, the call will not complete.

I have determined that if I go and change the outbound routing order, I can then then make a call. I am not sure if this is because it causes all trunks to re-register, or what , however I have done this seveal times now and every time it restores my ability to make calls