Phone Installation for Business

Hello - I'm looking for a skilled assistant who can help me set up US-based phone numbers for my business operations. The phone service should be a free to use service, otherwise we can look at subscription plans. However, we need to set up multiple phone numbers (at least 4 to start and will add more in the coming weeks). My assistants will need to be able to log in to each phone number, take calls and check the voice mailboxes setup for each associated phone number. It should be a one company service for all the phone lines and very easy to use.