The best way to get a job is to get a personal introduction to the hiring manager and build rapport with them. I would not ask for their manager's number. I would ask them to make an introduction. That will carry much more weight. A "Coffee Date" is a common way to have that initial meeting. It is perfectly reasonable to suggest (or have the person introducing you suggest) meeting over coffee. It's just a social nicety that can help break the formality of a first 'interview'.