UMTS 850 in USA
 

I have a UK Nokia 6500 slide which has
GSM 850 / 900 / 1800 / 1900
UMTS 850 / 2100

I will be visiting NY, Washington, Virginia, Maryland. I want to tether a laptop: I'm only interested in data. I am considering getting an AT&T SIM. I read that they use UMTS 850/1900 and I read that their coverage is better than T-mobile.

Is UMTS 850 available everywhere that there is AT&T 3G coverage? If not will I be OK with just UMTS 850 and not UMTS 1900?

Any recommendation for an AT&T SIM? Perhaps the one mentioned here if it's still available.

TIA
Dave

Since 850MHz reaches farther and so requires less base stations, which renders network rollout cheaper, I expect that AT&T's 3G coverage is primarily based on 850MHz, while the 1900MHz-band serves only to extend capacity in urban areas with high load. Unfortunately AT&T's coverage map doesn't disclose frequencies and you'll hardly find user reports on the web, as your phone's frequency configuration is very exotic. Usually UMTS850-capable phones do support UMTS1900, too. Actually I don't know of any other phone supporting only UMTS850.

AT&T has EDGE everywhere they have 2G coverage - something that might be useful.

Also note that AT&T prepaid service does not permit roaming on other providers, so when you look at the AT&T coverage map, be sure to look at the prepaid map and not the postpaid one. There are huge areas of the US (particularly the central and western US) where there is little to no AT&T native service.

Then again, while T-Mobile prepaid permits roaming, it doesn't yet permit true data access, just limited WAP - and their 3G is at 1700 MHz anyway.

It seems like my assumptions above are wrong. Wikipedia says:So you either need another phone or settle for 2G only.

I think it may be more complicated than that. Googling reveals there there are a lot of areas of the USA that AT&T has UMTS on 850 only. I think it depends on which original company (Cingular aka AT&T mobility, old AT&T, other?) was prevalent in an area. And I also read that AT&T is 'moving towards' 850. Many posts say 'You need an 850 phone for AT&T' - but it's often not clear whether that's for GSM (2G) or UMTS.

I found this site
WirelessAdvisor
which tells you (IIUC) who licenses the spectrum where. Plugging in a random place in Virgina: Shanadoah tells me that AT&T use UMTS 850. Or does it?

I assume that all US phones have 850 and 1900 - it seems odd that this one only has 850 if that's an unusual frequency. Maybe I'll try emailing AT&T.

@Photojim: thanks for the comment about prepaid - I would not have guessed that it matters. AT&T prepaid (aka Gophone?) reception seems OK in the area I mentioned in my OP. The phone does have EDGE.

North American-market 3G phones seem to always support both UMTS 850 and 1900. I guess it's the same issue we saw with tri-band 2G phones... they tended to support 900/1800/1900 or 850/1800/1900. With some providers that would be okay, with others it would be far from optimal.

Really, though, you have no choice here. Either you get a new phone, or you live with what AT&T gives you. :)

We have similar issues here in Canada. I am not certain exactly what frequencies are universally used (if any) for 3G - in dense urban areas it's certainly both 850 and 1900 as all the major carriers have spectrum in both frequency ranges - but we have the identical issue with 2G EDGE here. In the city where I live, it's at both 850 and 1900 MHz so my European tri-band 900/1800/1900 EDGE-supporting phone works perfectly, but at my cottage, EDGE is at 850 MHz and 1900 MHz is GPRS only. I get voice service, but very slow data service.

You can pick up a phone like a Nokia E63 pretty cheaply unlocked (that's my unlocked 3G phone until my ordered-this-morning iPhone 4 comes). That will give you the good 3G service here (granted, that particular phone is UMTS, not HSPA) and has quad-band 2G so you can use it in a pinch at home.

From what I understand, when 3G was 1st rolled out in the US, it was at 1900 MHz only, with 850 added later on (especially after the analogue shutdowns of 2008). Many cities that has only 1900 got 850 MHz overlays in 2009, which greatly improved coverage. My suggestion to you is to just try it if you don't want to buy a new phone. Given that wherever AT&T is licensed to use 850, they will want to use it, it would make sense that they would try to use 850 as much as possible for 3G. I bet you wouldn't be missing much by having only 850 especially if you're in a large 3G market like any of the major metro areas.