Direct Routing as a Service: The Complete Guide

SIPPIO helped pioneer Direct Routing as a Service, and we’ve set the standard for it across 80+ countries.

This is everything you need to know: what Direct Routing is, how delivering it as a managed service changes the picture, how it compares to Operator Connect, and how to choose the right path for your organization.

What is Direct Routing?

Direct Routing is a method for connecting Microsoft Teams to the public telephone network (the PSTN) through a carrier of your choice.

Microsoft gives you three ways to add external calling to Teams:

• Calling Plans, where Microsoft is your carrier and you buy numbers and minutes directly from them.
• Operator Connect, where a Microsoft-certified operator provides the connectivity through a managed program.
• Direct Routing, where you connect your own carrier to Teams using a Session Border Controller (SBC).

Direct Routing is the most flexible of the three. It lets you keep existing carrier contracts and phone numbers, negotiate your own call rates, and turn on calling in countries where Calling Plans and Operator Connect aren’t available.

For any organization operating across multiple regions, that flexibility is often the deciding factor.

How Direct Routing works

The SBC sits at the center of any Direct Routing setup. It’s the bridge between your carrier’s network and Microsoft 365.

When someone calls one of your Teams users, the call travels from the PSTN, through your carrier, into the SBC, and on to Microsoft, which delivers it to the right person in Teams. Outbound calls take the same path in reverse. The SBC handles the signaling and the media, and crucially, it manages the secure connection to Microsoft’s SIP interface.

That secure connection is where the ongoing work lives. The link between your SBC and Microsoft relies on mutual TLS authentication and trusted certificates, and the rules governing those certificates change over time.

Keeping the SBC patched, secured, certified, and compliant is a permanent operational responsibility, not a one-time install. More on why that matters below.

What is Direct Routing as a Service?

Direct Routing as a Service is Direct Routing delivered as a fully managed service.

Instead of buying and running your own SBCs, contracting carriers, and managing the security layer yourself, a provider operates all of it on your behalf: the infrastructure, the carrier interconnects, the certificates, the monitoring, and the compliance.

You consume Teams calling as a service and let someone else own the complexity.

The result combines the two things organizations usually have to trade off against each other: the flexibility and reach of Direct Routing, and the hands-off simplicity of a managed program like Operator Connect.

You’re not locked into one carrier or one set of countries, but you’re also not staffing a team to keep voice infrastructure alive.

Direct Routing vs Direct Routing as a Service

The question isn’t really Direct Routing or DRaaS, DRaaS is Direct Routing. The question is who runs it.

Self-managed Direct Routing makes sense if you have in-house telecom and SBC expertise, want maximum control over every layer, and have the appetite to own the maintenance, security, and compliance work that comes with it. Some large enterprises with dedicated voice teams genuinely prefer this.

DRaaS makes sense for everyone else, which is most organizations. If voice isn’t your core business, if you operate in multiple countries, if you don’t want to recruit and retain SBC specialists, or if you simply want predictable cost and someone accountable when something breaks, the managed route removes the burden without giving up the flexibility.

Put simply: self-managed Direct Routing is a project you own forever. DRaaS is an outcome you buy.

What about Operator Connect?

Operator Connect is worth understanding, because it’s a genuine option and often the right one.

It’s a Microsoft program where certified operators provide PSTN connectivity to Teams, managed through the Teams admin center. The operator runs the infrastructure, so like DRaaS, you’re not managing SBCs yourself. Setup is quick, and for organizations whose needs are well covered by an operator’s footprint and standard terms, it’s an excellent, low-friction choice.

The trade-off is flexibility. With Operator Connect you work within the operator’s coverage, rate structures, and capabilities. You can’t bring any carrier you like, customize routing as freely, or reach every country the way Direct Routing allows. For straightforward deployments that’s a fair trade. For complex, multi-region, or highly customized requirements, it can become a ceiling.

Direct Routing vs DRaaS vs Operator Connect

Here’s how the three managed-or-self-managed paths compare. (Calling Plans, where Microsoft is the carrier, is the fourth option but sits outside this comparison as it’s the least flexible and most limited in country coverage.)

The short version: Operator Connect trades flexibility for simplicity. Self-managed Direct Routing trades simplicity for flexibility. DRaaS is the option that refuses to trade.

Why self-managed Direct Routing is increasingly risky

Running your own Direct Routing was never trivial, but the operational risk has been rising, and the security layer is where it bites hardest.

The connection between your SBC and Microsoft depends on trusted certificates, and the standards governing those certificates keep moving.

A clear example: the June 2026 shift where TLS certificates must use the Server Authentication EKU exclusively to remain trusted by major browsers, and Microsoft has moved the Teams SIP interface to a new certificate chain to stay aligned. Every SBC using Direct Routing is affected. If your hardware doesn’t trust the new certificates in time, the secure handshake with Microsoft fails, and that means dropped calls, inbound and outbound, until it’s fixed.

This is the reality of owning voice infrastructure: it’s not a system you stand up once and forget. It’s a live responsibility with deadlines that don’t wait for you. Certificates expire and change. Security baselines tighten. Microsoft updates its requirements. SBC firmware needs patching. Miss any of it and the failure mode isn’t a minor degradation, it’s your phone system going down.

For organizations without a dedicated voice team watching this constantly, self-managed Direct Routing has quietly become a liability. The flexibility is still valuable, but the maintenance burden and the cost of getting it wrong have grown.

This is exactly the problem DRaaS and Operator Connect solve. With either, the provider carries the certificate, security, and compliance work as part of the service. The difference between them is reach and flexibility, but both take the operational risk off your plate.

If you’re relying on self-managed Direct Routing today, the honest question to ask is whether you’re confident you’ll never miss one of these deadlines.

Most organizations, on reflection, aren’t.

What to look for in a DRaaS provider

Not all DRaaS offerings are equal. When you’re evaluating providers, the criteria that matter most are:

• Genuine global reach: Can they deliver calling in every country you operate in, not just the easy ones? Multi-region coverage is where many providers fall short.
• Carrier flexibility: Can you keep your existing carrier relationships and numbers, or are you being quietly funneled toward theirs?
• Security and compliance as standard: Certificate management, SBC patching, and meeting Microsoft’s evolving requirements should be the provider’s job, fully included, not an add-on or your problem.
• Resilience and support: Voice is mission-critical. Look for built-in redundancy, real monitoring, and a support model with someone accountable when minutes matter.
• Microsoft alignment: A provider working closely within the Microsoft ecosystem will stay ahead of platform changes rather than scrambling after them.

A useful test: the things that make self-managed Direct Routing risky: security, certificates, global complexity, accountability; are precisely the things a strong DRaaS provider should make disappear.

DRaaS across multiple countries

Multi-country calling is where Direct Routing’s flexibility earns its keep, and where doing it yourself gets hardest.

Each country brings its own carriers, numbering rules, regulatory requirements, and emergency-calling obligations. Managing that in-house means multiplying every piece of operational work by every region you’re in. It’s a significant undertaking, and a fragile one.

Delivered as a service, that complexity is abstracted away. A capable DRaaS provider already has the carrier relationships, in-country compliance, and infrastructure in place, so you can turn on compliant Teams calling in a new market without building anything.

For organizations expanding internationally, this is often the single biggest reason to choose DRaaS over going it alone.

Migrating from self-managed Direct Routing to DRaaS

Moving from self-managed Direct Routing to a managed service is usually more straightforward than teams expect, because the underlying technology is the same, you’re changing who operates it, not ripping out how it works.

A typical migration involves reviewing your current setup, numbers, and carrier arrangements; porting or re-pointing numbers as needed; and transitioning users in planned phases rather than all at once. Done properly, it’s designed to be seamless for end users, with no loss of service. The right provider will plan the cutover around your business, not the other way around.

The payoff is immediate: the maintenance, security, and compliance burden you’ve been carrying simply goes away.

Frequently asked questions

• Is Direct Routing being discontinued? No. Direct Routing remains a fully supported way to connect Teams to the PSTN. What’s changed is the operational and security burden of running it yourself, which has made the managed route (DRaaS) more attractive for most organizations.
• Do I still need an SBC with DRaaS? Direct Routing always relies on an SBC, but with DRaaS, the provider owns and operates it. You get the benefit without buying, configuring, or maintaining the hardware.
• Is DRaaS cheaper than Microsoft Calling Plans? It depends on your call volumes, countries, and existing carrier rates. Because DRaaS lets you keep competitive carrier contracts, it’s frequently more cost-effective at scale and across multiple regions, but the bigger saving is usually in the operational overhead you no longer carry.
• What’s the difference between DRaaS and Operator Connect? Both are managed, so neither asks you to run infrastructure. DRaaS offers broader carrier choice, wider country reach, and more customization. Operator Connect is simpler but limited to a single operator’s coverage and terms.
• How long does it take to set up? Because the infrastructure already exists, a DRaaS deployment can be live far faster than building self-managed Direct Routing from scratch. Timelines depend mainly on number porting and how many users and countries are involved.

We can help

SIPPIO delivers Direct Routing as a Service across 80+ countries, with the flexibility and global reach of Direct Routing and none of the infrastructure to run yourself.

We handle the SBCs, the certificates, the security, and the compliance, so your team gets reliable Teams calling wh