Dumb question. Can I use this phone using a different country's SIM? I am planning to travel and would like to use another country's SIM.
I think you would need to be a customer for at least 30 days (this is what Verizon has done for customers who recently acquired a new phone through subsidized pricing). You might want to contact T-Mobile support to verify this.
Of course, you are still obligated to fulfill the duration of the service agreement