In FreePBX web portal, Add a trunk,

[didforsale] type=peer host=[IP ADDRESS OF OUR SERVER] nat=no canreinvite=yes disallow=all allow=ulaw allow=alaw dtmfmode=rfc2833 insecure=very context=from-didforsale

Please note: You can find the IP for DIDForSale upon logging into your account.  We send the calls to your public IP address and do not require any . . . → Read More: Configure Inboud DID with FreePBX and DID For Sale