Here is why, att unlimited isn't a true unlimited, after 5G it got reduced speed. with T-mobile I simply pay $70, got unlimited voice, texting, and 5G LTE with 5g mobile hotspot supported, no overage charge if exceed 5G, they even allow you to use your data oversea traveling w/o additional charge, texting is unlimited international as well. Same services with att its easy to go above $150.+ now they are offering 4 lines for $100, up to 10GB of 4G LTE data which is good for family plan. Last gotta mention their referral program, just talked to their reps, here is the copy of our conversation. "Chris: I'd be happy to provide you additional information about our Referral Program. Chris: When you refer one of your friends to T-Mobile and they activate service, both you and your friend can get unlimited 4G LTE data for a full year at no extra cost. This means you and your friend will be saving $30 per month for 12 months or $360 savings in a year. Chris: To take advantage of this offer your friend will need to transfer over their phone number from another carrier, then you and your friend will just need to register on our referral page within 30 days of your friend's activation of a new account. After both of you have signed up, your unlimited 4G LTE data will start that month. You: cool, what is referral page? Chris: Thank you! Please copy and paste this link: www.t-mobile.com/referral to visit our referral page. You: okay, appreciate it " then it's a no brainer, why not?