Newbie Question - Replacing T1/Strata DK16 system

I’m new to all things VoIP and phone systems. We currently have a (1) Fractional T1, (1) Toshiba Strata DK 16, (11) Toshiba DKT2020-SD Phones. We pay a small fortune for the T1 and are considering going VoIP to cut our cost. I’d like some recommendations as how to convert my system over to a VoIP system. We are looking at ordering a 50Mbps/10Mbps comcast business class internet connection. We also looked at their VoIP offering but I am confused as to what I need to make this work somewhat like our old system with one number ringing in on 4 lines etc, etc, and Comcast didn’t seem very informative. I was quoted $189 for the internet and $175 for the VoIP with 4 phone lines and a fax line.

If cost effective I’d love to go to an Asterisk solution with IP phones. I found recommendations to Telasip as a VoIP provider. With Asterisk do we only need a 4 channel sip trunk ( to replace the 4 channels we get on our fractional T1 or do we need something else? What phones are recommended that won’t break our bank? Any help or guidance appreciated.