I'm going to be the odd man out and say that I didn't care for Trac Phone's setup. We tried it with my son when he went on vacation with another family last year and I just really didn't like it. I didn't like that the minutes and activation expire so quickly. Also, it was such a headache because the phone that worked here ended up not working at the beach, it was roaming. I spent a couple hours total with trac phone's tech support and we did finally get the phone to work. But then I tried to add data to it and that set off another chain of events that required me to spend a bunch of time with the trac phone customer service. Oh, and even though the phone packaging had promised us double minutes, we never got them, and the foreign person at customer service either couldn't understand what I was trying to say to them about it or they were playing dumb, I'm not sure. I spent so much time on the phone with customer service over that stupid phone.
I've had a T-mobile prepaid phone for about 8 years now and I prefer their setup, so this summer I bought my son a tmobile phone and signed him up for a prepaid plan.
For emergency purposes, you can set up the tmobile account to automatically debit the minimum from your credit card and then you don't have to worry about it. The minimum to keep the phone active is $3 per month, that gets you 30 minutes or 30 texts (or a combination of the two). After that the minutes/texts will be billed at the rate of 10 cents each and you can set it up on their website to transfer a certain amount of money from your credit card into the t-mobile account each month. When the money runs out there's no more minutes until the next monthly $3 payment unless you choose to put more money into the account manually. I really like having absolute control over the account.
Then you can easily switch between types of plans if you need a better plan or data for a certain month. For example, this month my son went away with a friend on vacation again and I switched his plan to a data plan for the month, and I set it up to switch back to his regular plan at the start of the next billing cycle. Easy peasy.
My husband has the $25 unlimited talk and text plan and my son will have the same plan on his new phone this school year.