Peg, do an internet search for prepaid cell phones. It sounds like that's what you have, but there might be a better one for you. AT&T has one and so does Verizon. Then there is Tracfone, the granddaddy of them all. AT&T has one here that you pay only when you use the phone. I think it's $3 a day whether you use it for two minutes or two hours. But no charge at all for the days you don't use it.
We had a Tracfone as a second phone for a year or so. The problem with it is there wasn't service in the more rural areas of Oklahoma. And we spend quite a bit of time in rural areas.

So we got a second line on our regular cell phone. I gave the phone to my sister near Oklahoma City and she never had a problem with service. There have been so many towers built since then, it would probably work for us now.
With Tracfone, we had to pay to get the phone authorized. Then when you buy more time, it's automatically authorized for an additional 90 days. Or you can just pay an authorization fee without buying more time. Now that was several years back so you'd need to look at their current plans before you spend any $$ with them.