Yes, your wearable should be able to sync with your non-TMO device using Bluetooth, assuming coverage in your area is adequate from the other carrier. Samsung Gear S3 can be paired with both iOS and Android devices. If you use Data with Paired DIGITS for your wearable it must be paired to a T-Mobile phone number on the same account to use that phone number for calls and texts. At this time, the Samsung Galaxy Watch can only be paired with Samsung handsets.