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Learning, Sharing, and Teaching => Ask a Mustachian => Topic started by: bearman on March 02, 2013, 12:51:09 PM

Title: Two questions about my new telecom setup
Post by: bearman on March 02, 2013, 12:51:09 PM
Hi all - thanks to IP Daley's superguide and our AT&T plans coming to an end, we're planning to change cell providers and add VoIP. I have two questions before doing so:

--cellphones: right now we have two Windows Phones on AT&T. We'll be switching to a small H2O Wireless plan. My wife's phone's mic doesn't work without the headset. Because I don't use my phone very often, I'd like to swap phones with her. If we trade sim cards (after porting our numbers) will our phone numbers, settings, etc., switch as well? I'm guessing we'll need to back up the data and settings on the computer before swapping sims, and then re-sync. Mainly I just want to make sure the phone number will follow the sim.

--VoIP: Once we get this set up, how do you add multiple phones to the same phone number? For example, we'd like to have a phone in the kitchen and in the den in the basement.

Thanks for any pointers!
Title: Re: Two questions about my new telecom setup
Post by: Daley on March 03, 2013, 08:58:40 AM
Heya Bearman, welcome to the community! Let's get you some answers to your questions:

Cellphones: Your account with your provider is tied to the SIM card, not the phone itself, so yes... your phone number will follow the SIM card associated with it. Your configuration and settings of the phone itself and the phone's address book are tied to the handset. Technically, you can save your address book to your SIM card, but there's some limitations to that and almost nobody does it.

As for your wife's phone issue, if the mic doesn't work during calls but does during stuff like note recording, it might be a firmware issue/bug, and might be able to get the function back with a firmware update and a factory reset. Even if it doesn't, it's worth trying a reset anyway since you're switching phones as there's a slim chance it might fix the problem.

Finally, mind if I ask why H2O over Airvoice? Is it solely for the auto-refill option, or was there another reason? I only ask because outside of per MB data costs, Airvoice's $10/month plan technically gets you cheaper rates for texts and minutes unless you're doing H2O's $25/month package. Same MVNO network, and Airvoice's phone support is a considerable upgrade over H2O's these days.

VoIP: This is a trickier question, but it's not hard to work out once you know what you're tangling with. I'm going to be as technically accurate without being too complex as possible for the layman, but I'll be leaving out some of the more nuanced and technically accurate bits to the setup for the sake of brevity. (ha!)

First, we need to briefly address how landline phones get their ringer signal and what information you need to look at with your handsets and ATA. The ring signal is actually a higher voltage/amperage signal sent over the line, and back in the Ma Bell days, that high voltage/amperage signal drove a bell clapper. An old clapper style phone, rotary or touch-tone, had a REN (ringer equivalence number) of 1 and most phone companies provided you enough power to drive up to five of these phones on your traditional POTS lines. This means most phone companies provided you a line that could handle a REN value up to 5 with the phones used in the house without any troubles. In the more modern era with phones that plug into electrical outlets and have electronic ringers over manual, the amount of electricity needed to ring the handset lowered. Where each phone in the past took a guaranteed 1 REN, newer handsets and FAX machines and answering machines and the like would have a REN of <1, allowing for more phones/devices on the line. These numbers will be stamped on the bottom of any landline telephone you own. In cases where you have both a REN class A and REN class B value listed, that means the phone handles both phone and intercom functionality as well, so since both could theoretically happen at once, you need to add the REN A and B values together to get the phone's actual REN value, which could theoretically exceed 1 REN for that handset.

You follow so far? Good.

Now, with VoIP, you'll have what's called an ATA (analog telephone adapter). On this ATA will be your FXS (foreign exchange station) port that you will plug your telephone(s) into. Hidden somewhere in your ATA's documentation, you should find what the device's maximum REN output is. In the case of my Grandstream HT-286, the maximum REN load on my phone network is 3. This means I could reliably drive two old clapper style telephones, possibly three... but you never want to push right up against your limit as it's best to leave yourself an error margin to account for any resistance in the wiring, etc.

In our house, we have an old beater Vtech CS6219-2 two handset wireless phone system ($15 on sale a few year back) with a 0.1 REN and an even older slimline handset with CID with a 0.8 REN, both are REN class B devices. Combined REN value of our handsets is only 0.9, just a hare under the same current required to ring one old clapper phone. This means, with at least a 0.5 REN margin of error factored, that we could connect another 1.6 REN worth of devices on the ATA and still have them all reliably ring with incoming calls. You could split the line wiring with old school POTS RJ-11 line splitters ( or you can go out to the Demarcation Point (the box on the outside of your house where your old landline connects to your house wiring) and disconnect the phone company's copper which carries voltage even when its disabled (this is not recommended if you're running DSL for obvious reasons) to let you plug the ATA into your existing home wiring instead, but leave a huge warning sign about damaging inside equipment when you do. Full instructions here (

This should give you an idea of how to get phones to multiple rooms, however. So long as you don't exceed your ATA's REN value, you can drop as many splitters and cords as you like through the house to hook up handsets (the more splitters you use, the higher likelihood of noise on the lines, however - use the classic KISS engineering principle ( here), you can wire into the existing phone wiring in the house if you're feeling confident and brave enough (and most importantly know what you're doing), or you can just utilize a multi-handset wireless system.

Still with me? Excellent.

It's also worth bringing up the Achilles heel of VoIP while we're on the subject: electricity. Without electricity in your home, your VoIP provided home phone will cease to work. To ensure your system remains up for at least as long as your ISP's network is up in a power outage, you need an uninterruptable power supply, or UPS, and you need to connect your broadband modem, your router, your ATA and any phone(s)/wireless phone basestation(s) that require power to the UPS to ensure continued operation. In a crisis situation with extended blackouts, figure the POTS landlines, data connections through DSL or cable, and cell phone towers to have about 24-48 hours of battery reserves themselves. The higher the VA rating of your UPS, the longer it'll last, but it'll beep at you when there's no electricity (unless you modify it), but the other benefit is that you can turn it off and ration power for the devices if you need to ensure operation later. Added benefit of using a UPS in your setup is the added lifespan of the electronics as they'll be protected from damage by both brownouts and line surges, and they're good to hook a desktop computer up to for the same reasons.

As an example, I have my desktop, networking and telephone equipment all tied into a 1200VA/720W UPS with AVR (auto voltage regulation)... it's beefy, and it runs over $100 new (picked up on clearance for $65). To preserve power, I have the computer start shutdown if an outage exceeds 90 seconds, and then I have nearly the entire battery reserve for the UPS available to keep making calls and theoretically get online with the smartphone or laptop if necessary. I've never actually crunched numbers, but the UPS has provided at least 10-12 hours with the phone and network equipment in the past when left on. Still, it's something you should factor in with your decision making with equipment. If 911 services are a concern and you don't want to put all your eggs in the cellphone basket, consider a UPS.

Hopefully, that should get you (and likely others) going down the right path with your services.

(If you feel inclined, there's a couple ways for you to show your appreciation through my website (
Title: Re: Two questions about my new telecom setup
Post by: bearman on March 05, 2013, 09:16:54 AM
Hi Daley - thanks for the response.

Cellphones: All clear here now, thanks! I tried testing the mic on voice search, and it still didn't work. That said, after I swap sims, I will do a full reset and see if maybe that helps. I had chosen H20 over Airvoice (but not acted yet) because of the auto-reload feature. (One less thing to think about in life.) However, I'm still on the fence here.

VoIP: All clear here as well, thanks! This gives me a good roadmap as I look into hardware.

So, I think I'm all set for now ... thanks again!