The problem is that the phone number can be essential to verifying one’s ownership if the place. So Google is very careful not to let anyone edit phone numbers. Whemy did you not add it when you created the place?
I would personally forget about it. Alternatively, suggest the owner to claim the business. He will then be more likeky to be able to fix it.
I’m helping in numerous threads, so I am unable to remember earlier replies in other threads.
As mentioned in the other thread there are no tricks to get mobile numbers added. I believe the problem could be linked to India where I undertand there is no online directory covering all phone companies.
I think you should just let it fly. Getting obsessed with one detail is stealing time that can be spend more wisely.
I can not explain why a business can get approved with or without a mobile phone number.