Originally Posted by Redcoat:
“It may be the case that some or all 3G sim cards cannot handle the more recent security features implemented for 4G networks hence a 4G sim being required. In the early years of 3G coverage some networks turned off some security features on their 3G networks & sims to the point of being 2G backward compatible, so that if a customer was given a 3G enabled sim it would still work with many older 2G only phones. 3 was one that for obvious reasons didn't do this, hence their sim cards won't work on many antique 2G phones.”
“It may be the case that some or all 3G sim cards cannot handle the more recent security features implemented for 4G networks hence a 4G sim being required. In the early years of 3G coverage some networks turned off some security features on their 3G networks & sims to the point of being 2G backward compatible, so that if a customer was given a 3G enabled sim it would still work with many older 2G only phones. 3 was one that for obvious reasons didn't do this, hence their sim cards won't work on many antique 2G phones.”
If you look on other providers sites, such as Optus in Australia, they don't require customers to change sim cards to go from 3G to 4G.



