Cisco Recommendation?

[NetAdmin2004]

I have a T1 and a ISDN Prime circuit currently routed seperately. The ISDN Prime goes to an Adtran Atlas 550 then to the Phone Switch and the T1 goes to a Cisco 2620 Router to the firewall.....

I would like to combine the two circuits onto a Cisco Router and I am not familiar with how or if you can do this.

Any Suggestions on hardware or design? Any good sites to refer me to so I could get a little more educated?

Thanks!