I wish I could keep under 100 minutes…
You can switch over to the $30 plan you’re mentioning even if already have a plan with T-Mobile, and keep your number. Here is what I did (originally I had a $60/mo prepaid plan):
1) Buy a T-Mobile SIM (or “activation kit”) online for $1
2) When the SIM arrives, go online to t-mobile.com and activate it with the $30 100min/unlim/5GB prepaid plan. You’ll get a new T-Mobile number.
3) Call T-Mo customer service and ask them to transfer the phone number you have with your $60/mo plan to your $30/mo plan (you’ll need to give them both numbers and possibly SIM #s). Also ask them to cancel your $60 plan once the transfer is complete.
4) Wait a little… usually no more than 24 hrs, typically it takes much less. You should get a text notification on your $30/mo SIM/phone that your new service is activated, mentioning your old number.
5) You’re done! Enjoy your $30/mo savings 🙂