Apple ID Recovery

I have an issue with recovering an apple ID.

I bought an iPad from a friend who barely ever used it and it is his only apple device. Naturally he forgot his apple ID password and after multiple attempts to guess the right password we locked the ID.

We used the online steps on https://iforgot.apple.com/ to recover the apple ID. The message we got was that we'll receive an email on the apple ID with steps to recover the ID.

The problem we have is that we do not have access to the mail account. The only device we have access to is the cellphone number connected to the iPad.

Will we still be able to recover the apple ID?