Time for another installment. Let's talk hardware. If you have Vonage or CallVantage or Packet8, you've got a VoIP router. But it's "locked" meaning that it'll only work with the provider you got it from. Where can you get an unlocked VoIP router? Try the Voxilla store. Most of you will probably be interested in either the Linksys PAP2T (about $60 today) or the Linksys SPA3102 (about $80 today). Both are FXS devices. Well, actually, the 3102 can also function as an FXO device, as well. But, in both cases, you plug a regular old POTS phone into the router and you can make and receive VoIP calls with your POTS phone through your router.
S0, what's the difference between an FXO and an FXS? The difference is in the characteristics the router exhibits. See, there are two ends to a telephone line: the Central Office (or PBX) and the telephone handset (or keyset, in telephone company parlance). An FXO sits on the telephone end of the phone line and simply translates VoIP packets to POTS signals and vice-versa, acting as an intermediary between your phone and the VoIP system. An FXS acts like a Central Office or PBX, providing power, signalling and call routing as well as some ... well, some pretty neat functions.
And that's why you would spend the extra $20 to buy an FXS -- those function. With an FXS, you can assign extensions (I'm extension #101, my dog is extension #102, my cat is extension #103, etc.), program dial plans (select a VoIP service provider depending on the number being dialed, for instance), set up voicemail boxes (a real must if you assign extensions) and even do call routing (take an inbound PSTN call and route it to a completely different VoIP destination like your laptop at work, for instance). Pretty cool, huh? May be overkill for what you're trying to accomplish but, for 20 bucks, I say it's worth it.
OK, now's the time I quit and let it all sink in. Think about what I've said and think about what it would mean to have your own PBX in your house, a PBX that you control. Or just think about being able to get an inbound phone number for about $6/month including all the inbound minutes you can use. And think about being able to make outbound domestic calls for between $0.007/minute -- yes 7 tenths of a cent per minute -- and about $0.02/minute. How does that compare to your Vonage, all-you-can-eat plan for $28/month? Lessee ... $6 for unlimited inbound, so that means, to spend $22 on outbound calls, at $0.02/minute, I'd have to make 1,100 minutes of outbound calls. Sounds like a no-brainer to me.