SBC nat setup

Hi

Im new to setting up sbcs and was wondering if someone has a guideline or bcp on how to do the following:

I will be setting up a trunk to a service provider who will be doing natting on layer 3 and layer 7 headers, traffic to the service provider from my end will also be natted, they require the sbc subnet range and ip and will then provide natted ip details, im abit confused as to how to set this up

Thanks