2 phones

[JOHKEN78]

Only one phone can get signal at a time.

[Acrillix]

If you have a 3G Network Extender you need to turn off LTE.

If you have a 4G Network Extender you need to turn on LTE.

If you have a 3G Network Extender you need to make sure you don't have a WhiteList or BlackList

If you have a 3G/4G Network Extender you need to make sure you are close enough to the NE to connect