Which Betamax Voip provider do you use (that supports SIP)

I'm planning on ditching my Landline, going UPC for Broadband and then using VoIP for calls. I currently have a €10 "Free Calls" option with Vodafone but reckon I don't end up spending anything near €10 when compared to some VoIP providers.

The problem with all of the Betamax providers - http://www.backsla.sh/betamax - is that they vary their offerings. I see voipcheap.com has free ** calls to landlines (for up to 300 mins per 7 days). Then other providers in the group are doing these "free days" but I just don't understand what they are on about. My total usage last month was 500 mins so I think this would work for me. 90% of my calls would be to Irish Landlines and about 9% to Irish Mobiles.

However, most of all, I need a provider that supports SIP. I simply want to use my current phone device. I was looking at SmartVoIP.com but cannot find out if they support SIP or not. I plan to buy a Linksys SPA3102.

I feel my best option would be one primary supplier for landlines and a separate provider possibly for mobiles.

Any suggestions


C