• An Overview of American Mobile Networks

    Here in Australia, telco access is pretty straightforward, but if you're visiting the USA, how do you know if your phone will work there? And on which network? With the iPhone 5 and LTE, things get even more complicated. Even if you are not visiting the USA any time soon, the differences between Australian (and the rest of the world really) and American wireless networks is quite interesting. It's also incredibly nerdy.

    Here in Australia, we have Optus, Vodafone and Telstra. Every other telco (e.g: Amaysim, Woolworths, iiNet, etc) resells access to the network built by either one of those companies - called Mobile virtual network operators (also called MVNOs). In the USA, it's AT&T, Verizon, Sprint and T-Mobile. There are other smaller "regional" carriers like C Spire and MetroPCS, but they only have small coverage areas, typically only one or two states. There are dozens of MVNOs in the USA as well, reselling access on one of the four national networks.

    Verizon and Sprint are CDMA networks. You might remember Orange back in the day here in Australia, plus Telstra's network pre-NextG - those were CDMA networks, but they're well and truly phased out here. The iPhone 4S and iPhone 5 are "world phones" which support CDMA and GSM, so does that mean an Australian iPhone can be used on a CDMA network? Not quite. CDMA networks don't use SIM cards, so to get access to the CDMA network, you need to contact the telco and arrange for access. This means going on to a contract. No good if you're just visiting. If you're moving to the USA, it's no problem, if the carrier allows you to bring your on phone (which they often don't!).

    T-Mobile and AT&T are GSM networks - just like what we use here in Australia. AT&T's 3G network supports HSPA+ (up to 14.4mbit) and runs on the 1900Mhz and 850Mhz frequencies, both supported by all the GSM iPhones). Pretty obvious that all iPhones would work on AT&T, as AT&T is Apple's main US partner and the iPhone was exclusive on A&T until Feb 10th 2011.

    T-Mobile however, despite being a GSM carrier, use unique frequencies and as a result, all iPhones work on the T-Mobile network, albeit, only at 2G/EDGE speeds (i.e: slowly). For 3G data, T-Mobile use a mishmash of frequencies: 1700MHz, 1900MHz, 2100MHz are all in use for 3G on T-Mobile. 1700MHz, which is the predominate frequency they use for 3G/HSPA coverage, just doesn't work on any iPhone. T-Mobile support 2100MHz, which works on all iPhones, however, T-Mobile's 2100MHz coverage is sparse and not being expanded. That leaves us with 1900MHz, which all iPhones support too. Only recently, has T-Mobile started using 1900MHz in certain areas for DC-HSPA, which finally enables iPhones to use 3G services, on T-Mobile. T-Mobile is rapidly expanding their 1900MHz HSPA+ coverage, but details on where exactly there's coverage is difficult. All the info I can find is this blog post from T-Mobile stating that Seattle, Las Vegas, Washington DC and New York have it now.

    So that explains 3G coverage in the USA. Basically, Verizon and Sprint are unusable because there's no pre-paid services. T-Mobile is good because they sell outright pre-paid SIMs with no contract and are cheap, but there's fuck all 3G. AT&T is what you want to use, but getting a pre-paid SIM is tricky (even via an MVNO like RedPocket or Straight Talk). But what about 4G?

    LTE (aka 4G) is now in the mix and this changes everything, because all the carriers (Verizon, Sprint, AT&T and T-Mobile) are utilising LTE, which is SIM based - a big change for the CDMA based carriers Verizon and Sprint. The other thing to note with LTE, is that voice & SMS does not work over LTE. When you send an SMS (not an iMessage to another iOS device, but an old school SMS) or make a phone call, the phone will switch down to UMTS (or GSM if there's no 3G) and conduct the call/SMS that way, then go back to LTE when done. Eventually there will be voice & SMS over LTE, but not right now.

    Unfortunately, Sprint & Verizon are still ruled out for travellers now, as there's no pre-paid access to these networks. Even if there was, the LTE Bands they're using (Sprint - 1900MHz, Verizon - 700MHz, currently. New frequencies will be added in 2013 & 2014) don't work on an iPhone 5 purchased in Australia. T-Mobile have no LTE services at the moment. So they're no good either. That leaves us with AT&T, who are using band 4 (2100/1700MHz) and band 17 (700MHz) - neither of which is supported on the A1429 GSM iPhone 5 being sold here.

    So if you want to take an Australian iPhone to the USA to use on LTE, too bad, it's not gonna work. Maybe the 2016 iPhone (iPhone 6S!) will work on LTE in Australia and the USA, as the 700MHz frequency in Australia is currently used by analog TV and when that's phased out, 700MHz is very popular with telcos due to the better building penetration it offers over the higher frequencies. But that's so far away, it's not worth bothering with now.

    With all that explained, how does an Australian get access to one of these networks? Well, that's an article for another day. Unlike getting a tourist visa to the USA, it's not easy to get a US SIM card...
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