There are 4 types of telephone service currently available.
The most common service is Single-Line Analog, which includes a "beige retro" Model 2500 desk phone free of charge if desired,
but any "landline" phone from Walmart, Staples, Amazon etc. designed for residential service will work. If you're looking to install a desktop conference phone, these are normally analog also.
The second type of service is Multi-Line DTerm Digital. DTerms are primarily used by receptionists that need to monitor the status of and answer phones for others in the department. There are 12, 24 and 32 button models depending on the number of lines you need to monitor, otherwise they are functionally identical.
The DTerm phone is not included in the price of a new telephone number installation. A 12-button DTerm is $300, a 24 button $350 and a 32 button $400 and must be purchased from Telephone Services.
A third type of service is the DTerm IP, functionally the same as a Digital DTerm except it uses UTM's wired data network for connectivity. Costs for the IP are the same as the Digital DTerms. The IP model will be recommended when the cost of getting a legacy phone line to your location gets prohibitive and you already have wired data. The DTerm IP connects to the wall where your computer does now, then your computer plugs into the phone and "shares" your existing data connection. If you have a second data jack in your office, you can dedicate that to a DTerm IP, but if that second data jack isn't "active" there's a $200 activation fee, so it's often more cost effective for a DTerm IP to "share" a single data port with your computer.
The fourth type of service is rather new, it is a free single-line app for a mobile device and uses WiFi or Mobile Data to connect to UTM's Telephone System. This is great for the remote, mobile employee. Check your app store for "Univerge ST500" for details and screenshots if this sounds like something you'd be interested in.