Hello @Sandy73,
I know how important checking your usage is. I’d be more than willing to help show you how to do this.
You can definitely review your call history before your number was changed. This can be done this by going to MyAT&T > My wireless > Check usage > Data, text, & talk logs. Here, you can select the usage and time period you want to view.
I hope you found this helpful! Have a good rest of your day!
Jordan, AT&T Community Specialist