Unfortunately, T-Mobile doesn't typically extend its best cell phone deals to existing customers not activating a new line on T-Mobile. However, existing customers adding a line can often take advantage of deals for free or heavily discounted phones. At times, the carrier may extend partial deals to its existing customers if they meet certain deal terms and conditions.

Yes! The majority of T-Mobile's cell phone deals are trade-in deals. In fact, having a trade-in usually means getting the best deal from T-Mobile. Every once in a while, T-Mobile will instead offer BOGO deals, or just discount phones (usually older models), but for the most part, T-Mobile offers a ton of trade-in deals.

The T-Mobile Connect + 5GB plan is the cheapest plan you can get from T-Mobile. This plan starts at just $15/month and includes unlimited talk and text, as well as a hard data cap of 5GB. Don't forget to check out the cheapest phone plans available right now to pair with your plan.