Roaming and operator-updated time
I am writing this from India (GMT + 5.5) and roaming with my Singapore (GMT + 8.0) mobile phone. I noticed something very strange. In all my mobile phones, under “time and date” settings, I usually setup time zone as local time instead of GMT +/- X and Network operator time as auto-update. By this way, I hope to always have the current local time updated automatically. Everything seem to have worked fine until now…
In my Nokia E71, I noticed a time skew of around 2.5 hours (GMT+8-GMT-5.5 ?) when I switched on the phone after landing in the local airport. I thought the time synchronization hasn’t happened yet and waited. However, instead of correcting itself, the skew kept on becoming big and eventually it was 7 hours ahead of the local time. All my alarms, reminders would go off in the middle of the night waking us up even before we have actually slept 
I turned off and on again my phone couple of times and still the problem would not go away. Now, it was showing time as per GMT+7 time zone. At this stage, I wondered if it could be the operator issue and looked at my other mobile (iPhone) which was also setup to auto-update from mobile operator. There were no issues and the phone synced well and it always showed the correct local time.
At this stage, I started to wonder what could be issue ? there were 4 combination possible – home mobile network, roaming mobile network, phone model / manufacturer and time zone differences. I did a look up table. My Nokia E71 is on Starhub Network in Singapore, and was connected to the Vodafone IN network automatically and was showing GMT+7 time zone time. My iPhone is on SingTel in Singapore and was connected to the Airtel network automatically and was showing the correct GMT+5.5 time zone time. My primary suspect was the mobile operators’ algorithm in sync roaming mobile phones. Initially I thought, perhaps my mobile phone is in GMT+8 so there was a bug in time synchronisation and the network was pushing GMT+8+localtime. However, this was not the case as well. It was pushing down GMT+7+localtime. This left me with the only possibility of Singapore being registered as GMT+7 in the network operator. Incidentally, the natural time zone of Singapore is also GMT+7 (see natural time zone of singapore). Any way, all is theories and I don’t have any concrete solutions.
If you have experienced such issues and know of an possibility, do drop an comment.