Mister Money Mustache (MMM) has invited a friend to create a section on his website that he will keep updated that reviews many aspects of cell phone plans to save you money. There is no affiliate relationship so there is no bias. If you are paying more than $40 per month for your cellphone plan, you are probably paying too much. His plans are typically $15 - $20 per month, and are for people who are usually on wifi with their phones.
Check it out here: https://www.mrmoneymustache.com/coveragecritic/
A recent MMM column about this is here:
Introducing Coverage Critic: Time to Kill the $80 Mobile Phone Bill Forever" https://www.mrmoneymustache.com/2020/05/03/mobile-phone-plans/