How do I configure the router to allow me to access the Internet through our broadband connection when dialed in to the router?

First, make sure your remote client can call in, connect and access resources on the LAN. If you have a DSL router on the LAN that provides Internet access, then on your MTASR3-200, you need to configure it so the default gateway (or default route) points to the IP address of your DSL router.