Can the Verizon s6 edge work on 5-mobile?

[aokusman]

My brother has had a Verizon s6 edge for a while now using it on cricket. Recently he switched to simple mobile which operates on the t-mobile network but the phone will not pick up any signal. He called Samsung and sent the phone back to them. They returned the phone and still it's not working. It works with att, but not T-Mobile. He called Samsung and they said it's a Verizon thing that the Verizon s6 edge is not compatible with T-Mobile even though it's unlocked. I call BS and want to know if anyone has experienced this.