SIP gateways have many, many options—too many to list here; so, we'll review just a few.
First, you'll need to gather some information about the remote server to which you want to connect. The list generally includes the following:
The IP address (or hostname) and a port (the standard port is
5060) of the server that to which you are being connected
The username and password (if any)
How the carrier/gateway expects Caller ID to be handled (which SIP header the Caller ID should be placed in)
Whether registration is required
You'll also need to know the phone number format that your carrier expects when you send calls to them, and in which format they'll send calls to you.
Finally, you'll need to decide which of your existing SIP profiles you want to tie this gateway to. All gateways...