Just to add to Ronak's response:
The POTS-facing ports (PRI, BRI, FXO/FXS, E&M, etc) require DSPs to convert the analog or digital TDM audio into RTP packets. So, the dial-peer itself doesn't but any POTS interfaces it references does. This is not the case with VoIP dial-peers unless you need to do transcoding between codecs.
