From Boost Mobile's website:

With Todo Mexico PLUS - Stay connected with friends and family in Mexico and keep in touch with everyone back home when you travel to Mexico!

• Unlimited Calling from US to Canada and Mexico.
• Unlimited SMS from US to 200+ countries including Canada and Mexico.
• Unlimited Calling to US and Mexico while in Mexico.
• Unlimited SMS to Mexico and US while in Mexico.
• 1.5GB data while roaming in Mexico

​