said by bigjoesmith:I don't know how to do auto-failover, but you can select a provider by appending #2 (for the 2nd provider in your configuration) to the number being called. This works with my 580IP, and should work with the 610A IP.
So, 12125551111#2 would call 12125551111 using provider number 2.
I'm doing this exact thing with my gigaset and multiple providers after my default callcentric.
Unfortunately, this does not work with the C610.
(Unless it has been fixed with a recent firmware update.)