SMS timezone gotchabeen spending some time lately researching SMS technology. first off the whole industry is great, never seen so much jargon in my whole life (anyone doing i18n work will tell you, we simply love our jargon): SMSC, MT, PDU, MSC, HLR, MSISDN, yadda yadda yadda, bing bam boom, i could go on all day ;-) this stuff just rolls off your tongue.
one kind of subtle gotcha i've run into was timezones (tz). i'd always assumed it worked like email, you could control the display datetimes on the client as they were stamped with enough info to figure out how to display the email datetime in the client's tz. nope. what you get is either the aggregator's tz or the aggregator's service provider tz or some kind of compromise tz if the service provider handles many tz. whether or not your device can assemble it into your tz is another story.
if you're lucky or smart enough to handle just the one national market using a national aggregator/telecom, you'd never notice this. it bites your ankles though when you "go inter" as they say here in Thailand. depending on where the client device and aggregator's servers are located, you could get the rather cool phenomena of SMS coming from the future (shades of the 4400). well i think it's pretty cool, users however have a rather different opinion. no amount of cajoling or threatening will make any difference, you're stuck with that tz. probably something you might want to keep in mind.
you can read a bit more here.