Your phone system options, explained

Most schools and nonprofits choose from five kinds of phone service. Any of them can work well. They differ in what you buy, who runs the system, and how much setup and upkeep falls to your team.

This chapter walks through each option the same way: what it is, what you buy and manage, and what’s good to know. Then it compares them side by side and lists questions to ask any provider.

Note: Products and licenses change often. Each fact about a product or a law links to its source, with the date it was checked. Confirm the details with each provider before you decide.

Schools usually need the same few things, and that’s where the options differ most:

• Real desk phones in classrooms, offices and hallways, not only apps on laptops.
• Paging and bells, such as announcements over ceiling speakers.
• After-hours and closure routing, so the main line and the attendance line do the right thing at night, on holidays and on emergency closure days.
• 911 that sends the right location. Under federal rules for multi-line phone systems, anyone must be able to dial 911 directly, with no “9” first. The system must send a “dispatchable location”: the street address plus details like a building or room. If the system can do it without new hardware or software, it must also alert someone, such as the front office (Code of Federal Regulations, as of Oct 2026: 47 CFR 9.16; 47 CFR 9.3). These rules cover both on-site and network-based systems, including PBX and VoIP (Code of Federal Regulations, as of Oct 2026: 47 CFR 9.3).

For a full checklist, see What schools and nonprofits actually need.

On-premises phone system (PBX)

What it is

A PBX (private branch exchange) is a phone system that lives in your building. It’s a cabinet or server, usually in a network closet, that connects your desk phones to each other and to outside lines. The outside lines come from a phone company, either as traditional lines or as a SIP trunk, which delivers lines over an internet connection. (SIP, or session initiation protocol, is the common standard for internet calling.)

What you buy and manage

• The system itself: hardware, software and the licenses that come with it.
• Desk phones that work with that system.
• Outside lines from a carrier, on a separate bill.
• A maintenance contract, often with the dealer that installed it.
• Software updates, security patches, backups and spare parts.
• A replacement plan. Manufacturers set end-of-support dates for their systems, and help and parts can be harder to get after that. See Signs it’s time to replace your phone system for examples.

Good to know

• Desk phones: Some systems use only the manufacturer’s own phones. Others also accept standard SIP phones. Ask which models yours supports.
• Paging and bells: An on-site system can often connect to the paging amplifier or bell controller you already have, through an analog or paging port. Ask your dealer what yours supports.
• After-hours and closures: Schedules and holiday greetings are programmed in the system. Make sure more than one person knows how to change them on short notice.
• 911: Because the system is on your site, your team or your dealer sets up direct dialing, the on-site alert and the location for each phone. When phones move, someone has to update the location.

Hosted phone service (cloud PBX)

What it is

With hosted phone service, a provider runs the phone system in its data centers. Your desk phones and apps connect to it over your internet connection. You may also hear it called cloud PBX, hosted VoIP (voice over internet protocol) or UCaaS (unified communications as a service).

What you buy and manage

• A monthly service. Providers price it in different ways:
  • Per seat: a license for each person, usually with a set bundle of features.
  • Usage-based or itemized: you pay for each phone, number and feature you use, plus calling.
• Taxes and fees, which are often added on top of the advertised price. See How to compare quotes fairly.
• Desk phones, plus apps for computers and mobile phones.
• Your network: enough internet capacity, network switches that can power the phones, and settings that keep calls clear.
• Everyday changes, made by your staff in a web portal or by the provider on request.

Good to know

• Desk phones: Many hosted services work with standard SIP desk phones from more than one manufacturer. Ask which models they support and whether they set the phones up for you.
• Paging and bells: These often connect through a SIP paging adapter or network speakers that act like a phone extension. Ask which equipment the provider supports.
• After-hours and closures: Business hours, holiday calendars and phone menus are set in the provider’s portal. Ask how quickly office staff can switch the main line to a “school is closed” message.
• 911: The provider delivers 911 calls. Your team gives the provider a location for each phone and keeps it current. Ask whether locations can include a building and room, and who gets alerted when someone dials 911.
• Support: Ask who can call for help (any staff member, or only your administrators), during what hours, and how fast the provider responds.

Microsoft Teams Phone

What it is

Teams Phone adds phone-system features to Microsoft Teams, such as voicemail, call transfer, auto attendants (phone menus), call queues and caller ID (Microsoft Learn, as of Oct 2026: Microsoft Teams add-on licenses). Staff make and take calls in the Teams app on computers and mobile phones, or on desk phones that work with Teams.

What you buy and manage

• A Teams Phone license for each person who needs a phone number. Microsoft’s education guide says Microsoft 365 A5 includes Teams Phone Standard, and A3 users can buy it as an add-on (Microsoft Learn, as of Oct 2026: Meetings, calling, and chat).
• A way to call regular phone numbers. Teams Phone connects to the public phone network, called the PSTN (public switched telephone network), in one of four ways (Microsoft Learn, as of Oct 2026: PSTN connectivity options):
  • a Microsoft Calling Plan, where Microsoft is your phone carrier;
  • Operator Connect, where a carrier in Microsoft’s program supplies the calling and the numbers;
  • Teams Phone Mobile, where a mobile carrier’s SIM-based number is also the Teams number;
  • Direct Routing, where you connect your own carrier through a certified session border controller (SBC). An SBC is a device or cloud service that links two phone networks. You, a partner or a service provider manage it.
• A license for each shared phone. Some phones aren’t signed in as a specific person, such as phones in a hallway, lobby or classroom. Teams calls these common-area phones. Each one uses its own account and a Teams Shared Space license, and each license covers one device. Before April 2026, this license was called Teams Shared Devices (Microsoft Learn, as of Oct 2026: Microsoft Teams Shared Space licensing). It includes Teams Phone features, but you may still need a Calling Plan unless you use Operator Connect or Direct Routing (Microsoft Learn, as of Oct 2026: Set up the common area phones for Microsoft Teams).
• Resource accounts for phone menus and queues. Each auto attendant or call queue that answers calls directly needs a resource account with a Teams Phone Resource Account license. If it will send callers to outside numbers, that account also needs a way to make outside calls (Microsoft Learn, as of Oct 2026: Voice applications prerequisites and licensing).
• Setup in the Teams admin center: phone numbers, calling policies, devices and emergency locations.

Good to know

• Desk phones: Microsoft publishes a list of Teams-certified phones, and each listed model has a certification end date (Microsoft Learn, as of Oct 2026: Teams phones certified hardware). Check that date before you buy, since a classroom phone may stay on the wall for years. Some other SIP phones can sign in through Microsoft’s SIP Gateway if they’re on its compatible list. SIP Gateway supports basic calling, voicemail and message-waiting lights, but it doesn’t show presence (whether someone is available) (Microsoft Learn, as of Oct 2026: Plan SIP Gateway).
• Paging and bells: Microsoft’s documentation names overhead pagers as an example of analog devices. They connect through Direct Routing, using an analog telephone adapter (ATA) that the SBC vendor supports (Microsoft Learn, as of Oct 2026: Direct Routing: connecting analog devices). Ask your Microsoft partner how they would connect your paging and bell system.
• After-hours and closures: Auto attendants can follow separate call flows for business hours, after hours and holidays (Microsoft Learn, as of Oct 2026: Set up an auto attendant). Your admin can let “authorized users,” such as office staff, change those call flows without full admin rights (Microsoft Learn, as of Oct 2026: Set up authorized users).
• 911: With dynamic emergency calling, your admin maps parts of your network (subnets, Wi-Fi access points, switches and switch ports) to emergency addresses, so Teams can tell where a caller is (Microsoft Learn, as of Oct 2026: Configure dynamic emergency calling). An emergency calling policy can alert a security desk or front office by Teams chat, or bring them into the call (Microsoft Learn, as of Oct 2026: Manage emergency calling policies).
• Support: With a Calling Plan, Microsoft supplies the phone numbers and the support for your phone service (Microsoft Learn, as of Oct 2026: PSTN connectivity options). With Direct Routing, Microsoft says to contact your SBC vendor’s support first (Microsoft Learn, as of Oct 2026: Configure Direct Routing).

Google Voice

What it is

Google Voice is Google’s cloud phone service. For organizations, it’s an add-on subscription to Google Workspace, available with any Workspace edition (Google, as of Oct 2026: Voice FAQ for administrators). Google’s terms list Voice as an eligible add-on for the Google Workspace for Education editions and for Google Workspace for Nonprofits (Google, as of Oct 2026: Google Workspace Services Summary). Staff use Voice in a web browser, in the mobile apps, or on a supported desk phone.

What you buy and manage

• A Google Workspace subscription.
• A Voice license and a phone number for each user. Licensing is per user (Google, as of Oct 2026: Assign Voice licenses to users; How Voice billing works).
• An edition (Google, as of Oct 2026: Compare Voice subscriptions):
  • Voice Starter: up to 10 users, without auto attendants or ring groups.
  • Voice Standard: any number of users. Adds auto attendants, ring groups (several people answering one number), call queuing and SIP Link.
  • Voice Premier: adds automatic call recording, Google Vault, numbers outside your home country, and reporting through BigQuery.
• Supported desk phones, if you want them (see below).
• Setup in the Google Admin console: licenses, numbers, service addresses for 911, auto attendants and ring groups.

Google says discount pricing for registered education organizations is available through its Google Workspace for Education team or a Google Workspace partner (Google, as of Oct 2026: Compare Voice subscriptions).

Good to know

• Desk phones: Google supports specific Poly models: the ATA 400 and 402 adapters; Edge B10, B20 and B30; OBi 300 and 302; VVX OBi Edition 150, 250, 350 and 450; and the Edge E series. Google notes that Poly no longer sells the VVX, Edge B and OBi 300 models, though Google will keep supporting them. Google also notes that voicemail and the contact directory aren’t supported on Poly devices, and that a phone set up for Voice can’t use another provider (Google, as of Oct 2026: Desk phone requirements for Voice).
• Shared phones: Because licensing is per user, ask how a classroom or hallway phone that isn’t tied to one person would be licensed.
• Paging and bells: Google’s supported-device list covers Poly desk phones and adapters. If you need overhead paging or a link to your bell system, ask a Google partner how they would connect it.
• After-hours and closures: In Standard and Premier, auto attendants and ring groups can follow business hours and holiday closures, with a separate after-hours greeting and action (Google, as of Oct 2026: Set up a Voice automated attendant; Edit ring groups).
• 911: Voice sends each user’s service address to emergency services. Admins enter those addresses and keep them current, and changes take effect within 48 hours (Google, as of Oct 2026: Verify or change service addresses for Voice users). Admins can also set up email alerts for emergency calls. Each alert includes the caller’s registered location and phone number (Google, as of Oct 2026: Manage emergency call notifications). Google notes that emergency calling isn’t available during a power outage, an internet outage or a Voice outage, and advises using another phone service then (Google, as of Oct 2026: Call emergency services).
• Keeping a current carrier: SIP Link connects an existing carrier to Google Voice through certified session border controllers (Google, as of Oct 2026: Set up Voice for your organization).
• Support: Admins reach Google support from the Admin console by chat or email (Google, as of Oct 2026: Contact Google Workspace support). If you buy through a Google reseller, the reseller helps with billing and licenses (Google, as of Oct 2026: Contact your Google reseller).

Phone service from your internet or cable provider

What it is

Many internet and cable companies also sell business phone service over the same connection. Plans range from a few basic phone lines to a full hosted phone system.

What you buy and manage

• Phone lines or seats, usually on the same bill as your internet service, and sometimes on the same contract.
• Provider equipment on site, such as a modem or adapter with phone ports, and sometimes desk phones.
• Settings in the provider’s online portal, if the plan has one.

Good to know

• Bundles: A bundle can simplify billing, but it may tie your phone service to your internet contract. Ask about the term length, early termination fees, and what happens to the price when any promotional period ends.
• Features: These vary by plan. A basic line may include voicemail and caller ID but not phone menus, ring groups or paging. Ask for the feature list in writing.
• Desk phones and paging: Ask which phones and paging equipment work with the plan.
• 911: Ask how the 911 location is recorded for each line or phone, and whether it can include a building or room.
• Outages: Phones that run over your internet connection depend on that connection and on power. Ask whether the provider’s equipment has battery backup.

What you buy and manage

What surprises people

What surprises people: Teams Phone has two parts: the Teams Phone license, and a calling service that reaches outside numbers. If you choose Operator Connect or Direct Routing, the calling part comes from a separate carrier (Microsoft Learn, as of Oct 2026: PSTN connectivity options).

What surprises people: In Teams, shared phones need their own license. A hallway, lobby or classroom phone that isn’t signed in as a person uses a Teams Shared Space license, one per device, and may also need a Calling Plan (Microsoft Learn, as of Oct 2026: Microsoft Teams Shared Space licensing; Set up the common area phones).

What surprises people: Not every desk phone works with Teams or Google Voice. Teams uses certified models, or compatible SIP phones with basic features through SIP Gateway (Microsoft Learn, as of Oct 2026: Teams phones certified hardware; Plan SIP Gateway). Google Voice supports specific Poly models (Google, as of Oct 2026: Desk phone requirements for Voice). If you plan to reuse phones you already own, check the model lists first.

What surprises people: Paging and bells often need their own equipment. For Teams, Microsoft’s documentation connects overhead pagers through an analog adapter and a certified SBC (Microsoft Learn, as of Oct 2026: Direct Routing: connecting analog devices). With any option, ask which paging equipment the provider supports before you buy.

What surprises people: In every option, someone on your side enters and updates 911 locations. Google Voice uses a service address per user that admins keep current (Google, as of Oct 2026: Verify or change service addresses). Teams uses network locations that your admin maps (Microsoft Learn, as of Oct 2026: Configure dynamic emergency calling). On-site and hosted systems need a location for each phone. When people or phones move, the location has to move too. See 911 for schools, in plain English.

Questions to ask any provider

1. What’s the all-in monthly cost, including taxes, fees and any per-line charges? (See How to compare quotes fairly.)
2. What exactly do we pay for: each person, each phone, each number or each feature?
3. Which desk phones do you support? Will you set them up for us? How long will those models be supported?
4. How do shared phones in classrooms, hallways and the front office work, and how are they licensed?
5. How will overhead paging and bells connect? Which equipment do you support?
6. How do we change after-hours, holiday and emergency-closure greetings? Can office staff do it without IT?
7. How does 911 work? Can anyone dial 911 directly? Who gets alerted on site? How do we set and update each phone’s location, down to the building and room?
8. What keeps working during a power or internet outage?
9. Can we keep our current phone numbers? (See Keeping your phone numbers.)
10. How do you handle fax lines? For fire alarm and elevator lines, also ask your alarm vendor, since these lines need specialized, listed equipment.
11. Who do we call for help, during what hours, and how fast will you respond? Can any staff member call, or only our administrators?
12. How long is the contract? Does it renew automatically? What does it cost to leave early?
13. Will you sign our student data privacy agreement? If we leave, how do we get our call recordings and voicemail?

Tip: Send every provider the same questions and the same counts of phones, numbers and users. That makes the answers easy to compare.

When each option is a good fit

• An on-premises PBX can be a good fit if your current system is still supported, you have staff or a trusted dealer to maintain it, and you need existing paging, bells or analog equipment to keep working as they are.
• Hosted phone service can be a good fit if you want real desk phones in many rooms without running servers yourself. The provider handles updates and outside lines, and your staff make everyday changes in a web portal.
• Microsoft Teams Phone can be a good fit if your staff mostly work on laptops in Teams and you already run Microsoft 365, especially A5, which includes Teams Phone Standard. It suits organizations where most calls will happen in the Teams app, with IT staff or a partner who are comfortable in the Teams admin center.
• Google Voice can be a good fit if your organization lives in Google Workspace, most people need a phone number on their computer or mobile phone, and you need only a few desk phones from Google’s supported Poly list. Voice Standard adds the auto attendants and ring groups that a main office line usually needs.
• Phone service from your internet or cable provider can be a good fit for a small site that needs a few lines and simple features, when the bundle’s price and contract terms are clear in writing.

You can also mix options. For example, a school might put desk phones for classrooms and the front office on one service while staff keep using Teams or Google Meet for meetings.

Whichever way you lean, write down your requirements first (What schools and nonprofits actually need). Then ask every provider the same questions.