Side topic...received plenty of SMS from Mobifone to register or provide more info for sim card...
so went to Mobifone shop and bring along passport...can register up to 5 sim cards at one go...btw, they also ask you to smile for candid camera...
after repeated reminders and if dun register the sim cards, mobifone may disconnect the sim card usage...think applies to Viettel and Vinaphone too...this exercise required by the gahmen...