Verizon will not activate a phone onto their network that does not have their branding on it. Period. Game over.
For AT&T... Click the Pic in my sig and check out my guide... Matching Radios to Carriers: How To Run Unlocked. It pays to learn how to do this research.
If you have any further issues or questions provide some specifics on what phone including Model Name and, if known, RM-#. You can post that here or in the linked thread.