How to route long distance calls through another provider?

Hi,

I need help in configuring Trixbox to route long distance calls through another provider.
I have PRI connection from another provider and long distance through another provider.
As of now my local and long distance calls are routed through my exisiting provider.
The only info that my new long distance provider has given me is their
softswitch IP.
I need the configuration and steps.

Thanks