11 Replies Latest reply: Jun 4, 2008 9:07 AM by Michael Lafferty
Needing Widgets Level 1 Level 1 (0 points)
Does anyone know if AT&T, or the Iphone has the ability to update towers?

I had Alltel previously and I could dial *228 to update the towers.

My Own P4 Duo, Windows XP Pro
  • Lawrence Finch Level 7 Level 7 (32,750 points)
    I'm not sure what you mean by "update the towers". If you mean check which towers are being received the iPhone (any GSM phone) does that automatically.
  • Needing Widgets Level 1 Level 1 (0 points)
    Im not sure what it does myself. I am assuming it would update to any new towers put in place, and roaming towers that were new. All I know is that after updating, I could usually get some, or better service in places I couldnt before.
  • mapper65 Level 1 Level 1 (25 points)
    I was told a few years ago by someone at AT&T that they push roaming updates out which are stored on the SIM card. Back then I had a Blackberry and they said a reboot of the phone would put the changes into affect. Not sure if this hold true today and if the iPhone works the same way. Just my 2 cents worth,.
  • mapper65 Level 1 Level 1 (25 points)
    Verizon does a thing called *228 and you select option 2 which updates the roaming capabilities of the phone. There is supposedly a table stored in the phone that tell the phone that it can use specific towers owned by Verizon or others. Verizon will make agreements with other carries that are using the same technology as them and if you go into one of these areas you will unknowingly be using a tower owned and operated by this other carrier based on the roaming agreement. Likewise, from time to time a roaming agreement between carriers my be broken and when you rome into an area that you previously had service on then your service will be lost. I only know of one case where someone lost coverage in an area after doing a *228. I was told GSM does this automatically buy receiving push updates from you carrier so no *228 or similar procedure is necessary.
  • Tamara Level 6 Level 6 (13,730 points)
    He's referring to PRC updating like you do with CDMA phones. With Verizon, you dial *228 to update.
  • Needing Widgets Level 1 Level 1 (0 points)
    Thanks everyone. I am new to GSM technology.
  • Nathan C Level 5 Level 5 (6,260 points)

    My personal understanding is GSM phones don't keep a record of what towers are available per se. What it does is keep track of is GSM towers it can receive a signal from, and as long as it is getting what appears to be good signal from a given cell, it will stay connected to that cell. When it first communicates with the tower it passes along some information, and the tower verifies with the carriers if that phone is allowed on that tower. In addition, if the tower identifies itself as being outside your home area, the iPhone will turn off data (EDGE) if you have set data roaming to off.

    Turning airplane mode on for 30 seconds, or reseting the iPhone forces it to look for towers in the area again, and try to authenticate with the network again. When it authenticates, the carrier determines if you are allowed to use that tower at all or not. Authentication does occur over the air, and is based on the ICCID number stored on the SIM card.

    Hope this helps,

    Nathan C.
  • Needing Widgets Level 1 Level 1 (0 points)

    Thanks Nathan C.
  • Michael Lafferty Level 6 Level 6 (16,080 points)
    Cellular networks use what in predecessor radio systems was referred to as carrier voter receiving. Individual mobile handset transmitters are polled frequently to determine which transmitter-receiver pair represents the best signal at any given moment, and that path is used to intercommunicate. Cells are roughly concentric—as modified by terrain and man-made obstructions—and overlap, so that such polling often takes place with two or more tower sites.

    In practice, as you move from one place to another, your signal is effectively handed off from one tower site to another. This is particularly the case when low-powered, short distance femtocells are involved in the process, as you frequently move in such small zones from one site to another.
  • Needing Widgets Level 1 Level 1 (0 points)
    So would it be safe to say that phones will differ in signal power depending on the processor used to handle the signals (even though they are on the same network). If so, I wonder how the iphone would compare to the treo's and blackberries.
  • Michael Lafferty Level 6 Level 6 (16,080 points)
    Not so much the processor, but the radio: receiver sensitivity and transmitter power in a mobile handset are critical determinants of performance given identical proximity to a tower and similar factors which would interfere with or reduce a signal.

    Actually, you can probably determine a rough idea of how effective these units are comparatively by locating published specifications for the finished units, possibly in filings maintained by the Federal Communications Commission—who must approve mobile handsets and smartphones for use in the US—and from trade publications.

    Although, other than possibly adding an external antenna—which might well constitute a violation of FCC rules for your particular device—there is really nothing you can do to improve reception other than to relocate as you use the device, or use a device which takes advantage of UMA technology for 802.11x routing through a base station, use a femtocell if supported by your carrier, or set up a GSM repeater which effectively relocates the closest tower or tower array onto your premises.

    All of these technologies can provide substantially better fixed coverage, but mobile coverage is a different matter. You are, essentially, stuck with the signal strength of your carrier network in your particular geographic area, and with the existing sensitivity of your device.