If your team already uses Google Workspace, start with Google Voice. If it uses Microsoft 365, start with Teams Phone plus a PSTN calling solution. If you want a phone system that stands on its own, with its own app, add-ons and integrations, look at a dedicated provider such as RingCentral. Then, whichever you pick, settle two things before you sign: how each person’s 911 location is kept current, and how you’d take your numbers with you if you leave.

All three routes give each person a business number that rings on a phone app, a computer and, if you want, a desk phone, along with call routing that a single cell phone can’t do, such as auto attendants (“press 1 for scheduling”). The difference is mostly which software your team already lives in.

This guide is desk research from Google, Microsoft and RingCentral documentation and the Code of Federal Regulations, checked on October 9, 2026. No phone service was used hands-on for this page. Plan prices change and aren’t quoted here.

Three ways to get a business phone system

Google Voice Microsoft Teams Phone Standalone provider (RingCentral RingEX)
Fits teams that use Google Workspace Microsoft 365 and Teams Any suite
Rings on Mobile, laptops, supported desk phones, Gmail Teams desktop and mobile apps, certified desk phones RingCentral app and desk phones
Call routing Auto attendants, ring groups, call queues (Standard and up) Auto attendants and call queues Auto attendant included in RingEX
Phone numbers Google numbers, or another carrier’s via SIP Link From a separate PSTN solution RingCentral numbers

Google Voice

Google Voice can be added to a Google Workspace plan, and Google says a Voice line works on mobile devices, laptops and supported desk phones, with calls available inside Gmail. The plans step up like this:

  • Starter is for up to 10 users: one number on all your devices with call forwarding, unlimited US texting, voicemail transcription, three-way calling, call transfers and call recording, and desk phone and ATA support.
  • Standard has no user limit and adds auto attendants and ring groups, call queuing for ring groups, on-demand call recording, eDiscovery for calls, voicemails and texts, and SIP Link, which connects phone service from another carrier to Voice.
  • Premier adds international billing locations, automatic call recording and advanced reporting through BigQuery.

Google lists support for emergency dialing, spam-call blocking, number porting for admins, and sending calls to voicemail outside the working hours set in Google Calendar.

Microsoft Teams Phone

Teams Phone turns Teams into the company phone system. Microsoft’s documentation is clear that it has two parts: a Teams Phone license for each user, and at least one PSTN solution that supplies phone numbers and domestic, international and emergency calling. Calls between Teams users in your organization stay inside Teams.

Teams Phone works in the Teams desktop and mobile apps and on certified third-party desk phones, and it includes auto attendants and call queues. If your staff already spend the day in Teams, this keeps calls, chat and meetings in one place, but budget for both pieces, not just the license.

A standalone provider

A dedicated provider makes sense when the phone system needs to work the same way regardless of your office suite, or when you expect to add contact-center or AI receptionist features later. RingCentral is one example. Its RingEX plan FAQ lists voice, auto attendant, online meetings, team messaging, fax and conferencing, unlimited calls within the US and Canada, and more than 330 integrations with business apps. Business texting there is subject to RingCentral’s SMS content policies, including volume and frequency limits.

The 911 rules that apply to an office phone system

Federal rules cover both the phone system and the VoIP service behind it. Your provider handles much of this, but the setup choices, such as where each phone or user is registered, are yours.

Direct dialing and notification (47 CFR 9.16, Kari’s Law). A multi-line telephone system must let anyone dial 911 directly from any phone, without a 9 or other prefix, even if outside calls normally need one. Anyone in the business of installing, managing or operating the system must also set it to notify a central location where someone is likely to see or hear it when a 911 call is made, if the system can do that without new hardware or software. The notification can’t delay the call.

Dispatchable location (47 CFR 9.16 and 9.11). The system has to send emergency services the caller’s dispatchable location, which the rules define as a validated street address plus details such as suite or apartment where needed. Fixed desk phones must do this automatically. For phones and apps that move, including off-site use, the system must send an automatic location when technically feasible; otherwise it can rely on a location the user updates or the best available location.

Registered locations and warnings (47 CFR 9.11). For VoIP service that can be used from more than one place, a provider can rely on a Registered Location that the user can update at will, and it must detect when 911 is called from somewhere else and prompt for, or update, the location. Every VoIP provider must also tell subscribers, in plain language, when 911 may be limited, including if the equipment is moved, the broadband connection fails or power is lost, and keep a record that you acknowledged it.

What that means in practice: register an accurate address for every user and desk phone, tell remote staff to update their location when they work elsewhere, test that 911 dials without a prefix, and keep a mobile phone available for power or internet outages.

Keeping your numbers when you switch

Your main number is on your website, invoices and listings, so make sure you can take it with you:

  • VoIP providers must help you port. Under 47 CFR 52.34, an interconnected VoIP provider must facilitate a valid request to port a number in or out without unreasonable delay, and can’t enter an agreement that prohibits a customer from porting.
  • Ports have deadlines. Under 47 CFR 52.35, carriers that must port numbers have to complete a simple port, including one involving interconnected VoIP service, within one business day and a non-simple port within four business days, unless you or the new provider ask for a longer period.
  • Plan the cutover. Keep the old service active until the port completes, and get the account number and any port PIN from your current provider before you submit the request.

How to choose

  1. Start from your office suite. Google Workspace teams can add Voice to their plan. Microsoft 365 teams can use Teams Phone, as long as they budget for a PSTN solution as well as the license.
  2. List the routing you need on day one. If callers should hear a menu or reach whoever is free, you need auto attendants and ring groups or call queues (Google Voice Standard and up, Teams Phone, RingEX).
  3. Decide whether you need recordings or retention. Google lists call recording from Voice Starter, on-demand call recording and eDiscovery for calls, voicemails and texts on Standard, and automatic call recording on Premier.
  4. Check texting. Confirm whether business texting is included, which countries it covers, and what volume limits apply.
  5. Confirm 911 setup and porting in writing before you sign, using the rules above.

Phone systems are also a single point of failure: list yours with the other critical equipment in your asset replacement checklist. If you’re still choosing the office suite itself, read Google Workspace vs Microsoft 365 first, and when a staff member leaves, remove their line and reassign their number as part of your permission audit.

Frequently Asked Questions

Can we keep our existing business number if we switch to VoIP?

Generally, yes. Federal rules require interconnected VoIP providers to facilitate valid port requests and bar them from contracts that prohibit porting. Simple ports must be completed within one business day and non-simple ports within four, unless you or the new provider ask for longer.

Does VoIP work for 911 if the power or internet goes out?

Not necessarily. VoIP providers must warn every subscriber about situations where 911 may be limited, including moving the equipment, broadband failure and loss of power, and record that you acknowledged it. Keep a mobile phone or other backup for emergencies.

Do employees need to dial 9 before 911 on an office phone system?

They shouldn’t. Federal rules require multi-line telephone systems to let users dial 911 directly, without a 9 or any other prefix, even if the system needs one for other outside calls.

Sources

Checked October 9, 2026.