September 2007

I had lunch with a friend today (hi, Gary!). He tells me a common friend from a while back (you know who you are, Bryan 🙂 was reading my weblog and has some questions about dial plans.

Dial plan syntax can be specific to the manufacturer and, in some cases, to the router itself. PBX systems like Asterisk have their own syntax so if you want to get elaborate, you’ll likely have to port your dial plan if/when you change platforms.

On the other hand, you can insulate yourself from these differences by signing up with a virtual PBX provider like Voxalot or MySipSwitch. Of course, that means you’ll have to entrust them with your precious login information and, if they get penetrated, you could have your accounts hacked. It’s a decision that’s your to make. Me? I’ve signed up with both of them but I’ve still got my dial plans in my router. And, yes, they’re a bit more elaborate than what I’ve listed in my previous entry. For instance, 8XX calls are free with SIPPhone (see SIPphone) and a lot of other numbers, including toll-free, are available for free from FreeWorldDialup. So, my dial plan contains special routing to get 800, 866, 877 and 888 number to go to SIPphone and so on.

BTW, if you’ve forgotten how to reach me, one easy was is tony here at this domain. And don’t forget to OMIT the www.

I’ve had nearly a week of working with my SPA-3102 and I have to say that basic setup is a breeze. Within an hour of opening the package, I had it connected and was making and receiving VoIP calls. Another hour or so and I had my PSTN line connected and inbound calls were ringing on the phone I had connected to the FXO port. But this little piece of hardware has so many features and capabilities that I just couldn’t stop there. It can handle a total of 2 inbound VoIP accounts and six, count ’em, 6, outbound accounts. OK, two of the outbound are associated with your two inbound but, still, that’s a total of 6. And that doesn’t include the phone line from your phone company.

Things start to get a little tricky when it comes time to configure these various accounts and choosing one or another to dial your outbound call. I have accounts with SIPphone, FreeWorldDialup, Callcentric and a few others. The only account so far that has any outbound calling credit on it, though, is my Callcentric account. So, I need to configure my router appropriately and that means dial plans. What are dial plans? You can look it up in this Wikipedia entry but, for our purposes, let’s just say they’re strings which tell the router how to interpret the keys you hit on your phone’s handset. You could direct the router to

1) Send 311, 611 and 911 calls directly to your PSTN (i.e. dial the number through your telephone company’s line),
2) send all calls that start with “9” to the PSTN line (ditto),
3) send all calls that start with “#1” to your primary SIP provider, making a VoIP call to either another VoIP user or a PSTN line,
4) send all calls that start with “#2” to your secondary SIP provider (ditto),
5) send all calls that start with “#3” to your tertiary SIP provider (ditto),
6) send all other calls to your primary SIP provider (ditto).

This is, in fact, a slightly simplified version of what I have set up as my dial plan. And let me say it took a lot of forum-reading, thinking, experimenting and, ultimately, having a conversation with a VERY good friend to rationalize and simplify it. As a matter of fact, if you live with somebody and share your phone with them and they’re NOT a techno-nerd, I’d recommend you use something similar.

What else have I done? Calls that come to my PSTN line ring on the handset that’s plugged into the SPA3102. That means I can take ALL calls with that one handset. And, as you can see from my dial plan, I can dial PSTN calls from that handset, too. And that means that, ecept for backup in the case of a power outage, I don’t need to have a phone plugged into my PSTN line.

OK, time to back off again and let that all sink in. I’ll have more later. I still haven’t discussed all of this box’s capabilities.

I bought this Linksys SPA3102 from TelephonyDepot.com. It should be here later this week and, hopefully, I’ll have time to set it up in the very near future. VoipSpeak.net has a good guide to setting it up here and I’ll let you know how I fare as I go through the setup process. I’ll also be selecting dial-in and dial-out providers and will let you all know who I go with and what I think of their service.

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.