I just got an Android smart phone for my son as we needed to upgrade from the old CDMA network to Telecom XT network in New Zealand. We noticed he wasn't getting all of his texts, some would get through but most wouldn't. We tried unmounting the SD card and all the missing texts came flooding in, we thought we had fixed the problem but it hadn't, for some reason this solution never worked again!
We finally got onto a decent customer service person at telecom who put us onto a technician who knew what he was doing. The problem was a corrupt text blocking all the other texts, these corrupt texts can only be removed by a technician at their end, the corrupt text was removed and all the unsent texts came flooding into the phone. Problem solved? No!!!
The next day we were having the same problem, we got back in touch with telecom and this time we found out there was another corrupt text blocking the other texts. The difference this time was we were asked if the number 800 00 00 had any meaning to us which it didn't. The issue was sorted and the corrupt text was removed and we were informed that the corrupt texts were coming from telecom. If I understood correctly, and I may not have, the problem was the old network was sending texts that were not compatible with the new network.
Good one Telecom!!!