For any contact center, telephony is tied to customer trust. People call the numbers they know. Agents depend on the routing logic behind those numbers. Supervisors need recordings, reports, queue data, and clean handoffs when volume spikes. So, when someone says, “Let’s move voice into Microsoft Teams,” the next question is usually, “What happens to our existing carrier?”

Microsoft Teams gives organizations more than one answer. Microsoft Calling Plans are one option, but they aren’t the only one. With Direct Routing, Microsoft allows companies to connect a supported Session Border Controller, or SBC, to Teams Phone and use their existing telephony trunk. Microsoft also says organizations can bring existing carriers and phone numbers into voice channels through Azure Communication Services Direct Routing.

For companies already using Teams at scale, that’s a pretty big deal. Microsoft reports more than 320 million monthly active Teams users. If employees already work in Teams every day, the contact center conversation changes.

It’s less about replacing everything, and more about connecting the pieces that still make sense.

What “Bring Your Own Carrier” Actually Means

Bring your own carrier (BYOC) means you keep the telephony provider you already use, instead of moving every call onto a new provider because your contact center is changing.

For a contact center, that’s valuable, because a carrier contract isn’t just a monthly phone bill. It can include negotiated rates, regional coverage, toll-free numbers, service-level commitments, emergency calling arrangements, and support processes your IT team already knows.  

You don’t want to give up all that just because you’re updating your system. BYOC means you don’t have to. With a SIP trunk and direct routing, you get a connection that carries voice traffic over the internet between that carrier and your phone environment.

How Microsoft Teams Fits into the Picture

Microsoft Teams is already where a lot of employees take calls, message coworkers, join meetings, and check presence. It’s often where a lot of contact center work happens. After all, agents need quick access to people, context, and follow-up help when a customer’s question gets messy.

Teams Phone gives organizations a few ways to connect calling into that environment.  

Microsoft Calling Plans are the easy-button option. Microsoft handles the PSTN side, so there’s less carrier work for your team to manage. Operator Connect sits in the middle. You choose from Microsoft-approved operators and manage the setup through the Teams Admin Center.  

Direct Routing gives you the most control. It’s the route companies usually look at when they want to keep their current carrier, SIP trunk, phone numbers, or telecom setup instead of rebuilding that whole piece from scratch.

You can also use more than one PSTN connection type in the same tenant, which is useful for larger environments. A business might use Calling Plans for one group, Operator Connect for another, and Direct Routing for a contact center with more specific carrier needs.

Direct Routing: The Technical Bridge

Direct Routing is what makes bring your own carrier workable in Microsoft Teams.

It lets your existing carrier talk to Teams Phone through a supported Session Border Controller, or SBC. That SBC sits between your SIP trunk and Microsoft’s cloud phone system. It checks the traffic, translates the signaling, applies routing rules, and helps keep the connection secure enough for business voice.

Think of it as the border checkpoint for calls.

A customer dials the number they already know. Your carrier receives the call. The SIP trunk carries that call to the SBC. The SBC passes it into Teams Phone through Direct Routing. After that, you can decide what happens next. Maybe the customer hears an IVR menu. Maybe they go straight into a billing queue. Maybe skills-based routing sends them to the one agent group trained to handle that exact issue.

Direct Routing gives you a lot of control, but it does need proper setup. You’ll need Teams Phone licensing, a supported SBC, a public IP address, a fully qualified domain name, public DNS, and a trusted public certificate for the SBC. None of that should scare a capable IT team or an experienced partner. It’s standard voice work. Still, it’s the kind of work you want planned before anyone starts moving customer calls around.

Direct Routing is the bridge. But the bridge needs to be built properly. For contact centers, that means clear ownership between the carrier, SBC provider, Microsoft environment, and contact center vendor before calls start flowing through it.

What This Means for Your Contact Center

A carrier change sounds tidy in a planning deck. On the floor, it gets personal fast.

The billing team cares because customers still call the same toll-free number printed on statements. Supervisors care because they need live queue data when wait times start creeping up. Compliance cares because recordings and retention rules can’t disappear during a voice migration. Agents care because bad routing turns a normal Monday into a transfer marathon.

That’s why BYOC matters. It lets the carrier piece stay put while the contact center moves closer to Teams. Still, direct routing gets the call into the Teams environment. After that, the contact center still has real work to do:

• Decide which queue gets the call  
• Route by skill, location, language, urgency, or customer type  
• Play the right IVR menu  
• Record the interaction when policy requires it  
• Show supervisors what’s happening in real time  
• Give agents customer context before they answer  
• Support voice alongside chat, email, SMS, and other channels  
• Keep reports clean enough for operations teams to trust  

Teams Phone does include auto attendants and call queues. For a smaller team, that might be enough. For a contact center handling billing issues, claims, outages, healthcare appointments, service escalations, or regulated conversations, you need more muscle around the call.

This is where certification becomes more than a badge. Microsoft recognizes three Teams contact center models: Connect, Extend, and Unify. Connect matters most for BYOC because it uses certified SBCs and Direct Routing. Extend and Unify matter because they show how deeply a provider can work with Teams as Microsoft’s contact center approach keeps moving.

ComputerTalk is certified across all three models. For a team trying to keep its carrier while modernizing the contact center, that range matters. You don’t want a vendor learning Teams telephony on your busiest queue.

Why Organizations Choose BYOC for Microsoft Teams

Most companies don’t choose BYOC because they’re attached to telecom complexity. They choose it because the carrier setup they already have is doing a job and usually doing it well.

Maybe the contract still has two years left. Maybe the organization gets better rates through an existing carrier deal. Maybe a local provider handles a region better than a standard calling plan. Maybe compliance has already approved the current telecom path, and nobody wants to reopen that review unless there’s a good reason.

Those are practical reasons. They show up in budget meetings, migration plans, and risk reviews.

Common reasons organizations keep their carrier include:

• Existing contracts: Early exits can bring penalties, awkward renegotiations, or wasted spend.  ‍
• Negotiated rates: In a high-volume contact center, pennies matter. A tiny difference in per-minute pricing can turn into a very real budget issue once thousands of calls start adding up. ‍
• Regional coverage: Local or preferred carriers may offer better support in certain countries, provinces, or service areas.  ‍
• Compliance comfort: Some industries already have approved voice paths for recording, retention, emergency calling, and regional rules.  ‍
• Control: IT teams may want more say over routing, failover, and how voice traffic moves.  

There’s also a staffing angle to think about. Service teams are already stretched. Salesforce found that 77% of agents say their workloads have become more complex, and 69% of service decision-makers say agent attrition is a major or moderate challenge. A messy voice migration adds unnecessary pressure to those teams.

BYOC keeps one major piece of the puzzle steady while the rest of the contact center moves forward. It won’t make the project effortless, but it does mean there’s one less massive change for IT, agents, and finance, to absorb all at once.  

What to Look for in a Teams Contact Center That Supports BYOC

A Teams contact center can say it supports BYOC. That doesn’t mean the setup will be easy with every carrier. Before you commit, ask how the platform actually handles Direct Routing, SBCs, carrier choice, and day-two support. The sales demo won’t show the awkward parts, like who gets called when a toll-free number stops routing properly at 8:40 on a Tuesday morning.

Look for a provider that can answer these questions clearly:

• Is the solution Microsoft-certified? Microsoft certifies Teams contact center providers across Connect, Extend, and Unify models. Certification doesn’t solve every problem, but it proves the vendor has gone through Microsoft’s compatibility and reliability checks.  ‍
• Does it support Direct Routing properly? BYOC shouldn’t depend on brittle workarounds. If you’re keeping your carrier, Direct Routing needs to be part of the real architecture.
• ‍Which SBCs are supported? Microsoft only supports Direct Routing with certified SBCs. Ask whether the vendor helps with SBC planning, troubleshooting, or partner coordination.  ‍
• Can the platform support more than one telephony path? Some organizations use Direct Routing for the contact center, Operator Connect for another group, and Microsoft Calling Plans elsewhere. That mix is normal in larger environments.  ‍
• Do you keep full contact center functionality? BYOC shouldn’t mean giving up IVR, routing, recording, reporting, monitoring, CRM context, or omnichannel service.  ‍
• Who owns support when something breaks? Get this clear before launch. Carrier issue, SBC issue, Teams issue, routing issue, contact center issue. Someone needs to know where the handoff sits.  

ComputerTalk’s ice Contact Center supports Direct Routing, Operator Connect, Microsoft Calling Plans, ComputerTalk carrier services, and bring-your-own telephony. Plus, ComputerTalk is certified across Connect, Extend, and Unify. That gives organizations room to keep today’s carrier strategy while leaving space for whatever their Teams roadmap looks like next.

Keep the Carrier, Modernize the Contact Center

BYOC works because it respects the fact that most organizations aren’t starting from zero when they decide to modernize their contact center.  

They already have carrier contracts, numbers customers know, SIP trunks that work, regional telecom relationships, and routing decisions made for good reasons. Throwing all of that away just to move closer to Microsoft Teams can create more risk than value.

Direct Routing makes the move feel a lot more practical. Your carrier can stay. Calls can flow into Teams through a certified SBC. Your contact center still handles the pieces your team depends on every day, including IVR, routing, recording, reporting, monitoring, and the agent experience.  

That’s the setup most organizations are really looking for. Agents can work in a place they already know. Supervisors can keep an eye on live activity without hunting through disconnected systems. IT still gets control over the voice architecture instead of handing the whole thing off and hoping it behaves.

It also gives you room to adjust later. Direct Routing might be the right fit now. Operator Connect could make sense for another part of the business later. Deeper Teams contact center models may come into play as Microsoft keeps developing the platform.  

For organizations that want to keep their carrier and still modernize the contact center, ice Contact Center for Microsoft Teams fits that brief well. Contact ComputerTalk to talk through the move to Microsoft Teams telephony and the cleanest path for your current voice setup.