AT (AirtelTigo) started to issue USIMs recently

With the new USIM, 4G could be used when it becomes available.
In contrast, with the old SIM, even if there is 4G signal available, only 3G/2G signal could be used.
One may consider a SIM replacement now in order to avoid queuing when 4G is announced.
SIMs with only TiGO, Airtel, or Glo are unlikely to be USIMs.