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tomz17
join:2004-01-09
Newark, NJ | FCC I wonder how this will work
#1 : All cell phones in the US (and most civilized countries) operate in regulated licensed spectrum (FCC in the USA). Billions were spent on this spectrum at auction. When your carrier sells you a femtocell it comes with a GPS receiver so that it can use only spectrum owned by that carrier in that particular part of the country. Your phone radio is simply physically incapable of tuning to an unlicensed band (900/2.4, etc.)!
Furthermore, each carrier has techs which check for interference infringing on their spectral property (e.g. a leaky transmitter from another cell phone provider). If you live in a mildly populated area and turn on a femtojack with power for 3,000 sq ft. of coverage, the FCC WILL come knocking on your door.
#2. Roaming profiles in modern phones are run off of very long and very complicated lists. Your CDMA (verizon/sprint) phone has a PRL which typically forbids association with any network not on the list (it is also set to favor the native network over any other). Your femtojack will NOT be on the PRL list unless you edit it on your computer in a mildly complicated procedure -or- alter the home-sid in your NAM! Verizon + Sprint account for WELL OVER 50% of the US cell phone market.
This *has* a chance of working on a GSM phone (t-mobile / AT&T), unless carriers specifically start restricting their sims (I think this is possible but might be against GSM spec). In any case, once your phone associates with the femtocell, you will not get any incoming calls, texts, etc. | | |
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NyNexit
join:2009-11-01
Huntington, NY | good info thanks ! | |
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 ·Acanac
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said by tomz17: In any case, once your phone associates with the femtocell, you will not get any incoming calls, texts, etc. This part is wrong. Once your cell associates with the femtocell, you WILL be able to use your phone as if nothing happened. That being said, you'll be charged the tariff of that particular Femtocell's network operator, in this case magicjack.
Another thing to keep in mind is that carriers CAN and WILL forbid your SIM card from connecting to specific networks so they can VERY easily counter this.
Adi | |
tomz17
join:2004-01-09
Newark, NJ | said by adisor19:said by tomz17: In any case, once your phone associates with the femtocell, you will not get any incoming calls, texts, etc. This part is wrong. Once your cell associates with the femtocell, you WILL be able to use your phone as if nothing happened. That being said, you'll be charged the tariff of that particular Femtocell's network operator, in this case magicjack. Nope... I stand by my original statement. Unless your operator is set up to roam on a network (from their end), your phone will just appear to be out of its service area. Calls will go straight to voicemail, texts sit in queue, etc. Magic Jack needs the full cooperation of your cell carrier to pull off incoming calls/texts.
said by adisor19:Another thing to keep in mind is that carriers CAN and WILL forbid your SIM card from connecting to specific networks so they can VERY easily counter this. Adi AFAIK, standard GSM just has facilities for a small "preferred" network list on the sim. I believe about 25 entries without any additional access information (i.e. you can still choose to use networks not on the list... the list is just there to guide the "automatic" network selection on the phone). This is NOT the same as an IRDB or PRL. This is why I was *more* optimistic about this working on GSM handsets. Everything else is controlled network-side. However, I bet there are clever SIM hacks (outside of GSM specs) you can pull off to block access to particular network. The question is only how motivated your carrier will be to actively block magic jack, and whether they can do so on existing sim cards. | |
patcat88
join:2002-04-05
Jamaica, NY
kudos:1 | said by tomz17:AFAIK, standard GSM just has facilities for a small "preferred" network list on the sim. I believe about 25 entries without any additional access information (i.e. you can still choose to use networks not on the list... the list is just there to guide the "automatic" network selection on the phone). This is NOT the same as an IRDB or PRL. This is why I was *more* optimistic about this working on GSM handsets. Everything else is controlled network-side. However, I bet there are clever SIM hacks (outside of GSM specs) you can pull off to block access to particular network. The question is only how motivated your carrier will be to actively block magic jack, and whether they can do so on existing sim cards. In GSM roaming, your roaming carrier will make a circuit between the SIM card in your phone, and your home carrier. Your home carrier will approve or deny every roaming attempt in real time, so the need for very long PRLs like on CDMA isn't needed with GSM. Geographically limiting roaming is done by the home carrier in real time, not a fixed list in the phone. | |
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