Effective August 3, 2020 the Federal Telecommunications Institute of Mexico has implemented a new standard 10-digit dialing plan. 

• All phone numbers need to be dialed through a 10-digit dial plan
• The "01" prefix used on Long Distance, 800 and 900 numbers will no longer be required (i.e. Long Distance "00", Country Code "52", called party number in 10 digit format "8112345678")
• 044 and 045 will no longer be required when dialing mobile numbers

You can view additional information on these changes and the implications here.