Default Google Nexus Phones on Tmobile lose signal outside USA!!

Has I missed but has anyone tried using the nexus 5 with a T-Mobile Sim outside USA? It doesn't work. I never knew it was the phone until I took a old unlocked from Att phone with me and as soon as my nexus lost signal I popped my Sim in the iphone and got full signal. Next I tried with a T-Mobile Galaxy s4 nexus lost signal S4 worked like a champ. Called google and the first person I talked to told me it was a known issue and her husband takes a back up phone when he travels. The next person told me to call Tmobile.

Sent from my Nexus 5 using xda app-developers app