Optimum voice asterisk

i currently use optimum voice (cablevison) who has provided a Motorola sbv4200 voip cable modem. I have this extended to an analog phone. I want to use asterisk at home and I am unsure of what I will need.

Can I just extend the line from the modem into an external sip capable Analog adapter of some kind? And then use a sip based softphone with Asterisk? Is there a better way?

Thanks for any suggestions.

I’m trying to do the same. However I dound a problem. Wehen I connect the analog output of my modem to the pstn port of my x100p I loose dial tone on all of my phones.

the analog output of the cable modem is a just from some sort of VOIP to analog converter.