Several options.
1. Have your phone unlocked. Get a digicell sim card. Load credit on triple up days only. Call mom in evenings or on weekend. Minimal rate.
2. Download Facebook Messenger on Mom's phone before leaving (as well as yours), call (when connected to wifi) anytime, anywhere, talk as long as you want for free.
3. Buy a cheapie phone from SMART (my personal fave). Buy minutes on triple up day (50.00 and up gets triple credit). Use that credit to purchase to buy text bundle, international text bundle, call after 8 pm or weekends. If you buy an android from SMART, you will get 3g service! Use your triple credit to buy data package for internet service! Basically you will have free internet, international texts and text messages and still have credit for phone calls in Belize or wherever.
And, of course, Number 3 is my favorite!!