I recently purchased a new phone system and do not have anyone on-site to manage it. Do I need to hire someone to manage it internally, or can I outsource the service?

Without any of the questions above answered, I would say that you would most likely need to hire/train someone to manage it. This is purely based on the fact that you said "purchased" in your question. Management of any premise based hardware system typically falls to the company that bought it. There are outsourced telephony services in the form of hosted and managed providers, but these companies usually operate as a subscription service and require you to use their hardware/handsets. You could also find local/regional telecom consultants to periodically work with your system, but it would not be a cost-effective solution for ongoing management.

Unless your phone system is supporting 100+ more employees you should ask the manufacture of your phone system for a service company in your area to work on your system.

Normally once the system is set up completely and working the need to have additional programming. Ads, moves or changes are occasionally required.