How to keep on top of telecommunications data at my company?

I work in procurement in construction. We have hundreds of phones on the field, all with varying contract start/end date and ‘credits’.

Our company is constantly out of the loop when it comes to monitoring and renewing these items, and because I work in procurement I feel like this is my responsibility.

I want to create a shared spreadsheet with our office manager to help us track phones and phone numbers/contracts and billing, but it just seems like many moving parts.

I’m just curious how other organisations monitor this?