Most companies need just one number, but some companies need several numbers because they have:

Several branches. For example, a chain of beauty salons, where each salon needs a separate number. Employees won't have to distribute requests to branches - clients will write to the right place;

Several departments. For example, the sales department would have one Telegram account, and HR would have another Telegram account; then job applicants would go to HR, and clients would go to sales.

Different groups of customers that different people work with. For example, retail customers are handled by some salespeople and wholesalers by others;

Each manager has a different number. This is the case for those guys who handle big deals, like selling real estate or cars, and work with the client personally. They usually have business cards with a personal number on them.