I have SOHO and currently have 2 lines from Qwest. Minimal Long distance. Fax only occasionally.

Tired of paying $75-80 per month for basic residential phone package with only caller ID installed; I'm looking for different options.

Have any of you set up SIP trunking, especially if it was on DSX-40 that can give me ideas on options, and how to proceed?

Goal is to reduce cost.

I went on NEC dealer site and saw that there are a bunch of SIP certified or tested providers, which tells me that not all SIPs are created equally.

I would only need the 2 lines with single number OK, or whatever it's called in SIP world. No 800 # needed. Incoming Fax handling would be nice. Caller ID would be great. No other routing or voicemail as the NEC PBX already has that.
If the SIP can call house and cell at same time, and do other cool things, that's just an icing on the cake.

Besides picking out a SIP provider, your DSX-40 will need a VoIP card in it. You may also need to check and see if your router and switch, if used, are SIP-capable.

This organization is a good resource for all things SIP:

[Link: siptrunk.org]