Post the regulatory relaxations offered by the 23 Jun 2021 for OSP, we expected that companies would start pushing their call center systems more aggressively in India. After all, for the call center industry, the 2021 regulation was the telecom equivalent of India’s business reforms of 1991 – a game changer.
India’s OSP regulation has often been a real challenge for call centers – onerous and ridden with red tape. But, spurred by the Covid pandemic, which effectively paused office work, the government in successive regulations relaxed the OSP regulations further and further. The 2021 regulation effectively concluded that it was time for the industry to self-regulate – the for DoT to step back from being a schoolteacher checking everyone’s homework. The other thing this regulation enabled is that it allowed products such as MS Teams, Zoom Phone, RingCentral, and Genesys Cloud to begin operations in India. It still hasn’t been a straightforward road for them, but for each of them, things have been steadily falling in place.
In this article, we break down how MS Teams Direct Routing (DR) operates within this regulatory context, and how enterprises that intend to use this capability can remain compliant with India telecom norms.
But first, the regulatory background
Until the June 2021 OSP reforms, India required:
- Call centers to register under the OSP regime.
- OSPs to maintain physical separation of PSTN and data networks.
- Use of leased lines/MPLS for interconnects.
- No interconnect between voice/data resources across OSPs without strict control.
Global CCaaS platforms were effectively excluded from the Indian market because:
- They lacked Indian telecom licenses and could not legally terminate PSTN calls in India.
- Media paths often routed internationally, and deploying that model in India would violate data localization and call termination norms.
- They did not provide government-auditable CDRs within India.
Post-23 June 2021, OSP registration was scrapped, and virtual setups were allowed. But key telecom rules remain:
- Only DoT-licensed Indian telcos can offer PSTN connectivity.
- Media and signaling for Indian PSTN calls must stay within India.
- Foreign entities cannot hold access licenses.
What is Direct Routing (DR)
With MS Teams Direct Routing, enterprises can connect their own SIP trunks (typically through a Session Border Controller, or SBC) to Microsoft Teams, which enables PSTN calling through MS Teams itself. Yes, this lets users place and receive calls to/from regular phone numbers from within Teams.
How it works:
- The enterprise purchases a PSTN SIP trunk from a telecom provider. Currently, Microsoft has partnered with Tata Telecom, Tata Telebusiness Services, and Airtel for this, so you have to purchase the SIP trunk from them only.
- A Microsoft-certified SBC is deployed (on-premises or hosted), which connects:
- To the telecom provider (via SIP)
- To Microsoft Teams (via Microsoft Phone System APIs)
As can be seen from the architecture diagram below, this setup effectively acts as a bridge between Teams and the telephone network.
Where the rubber meets the road
If you have a MS Teams DR setup in India,
- A call made via PSTN to an employee in your company would first traverse the PSTN network, hit the TSPs SIP trunk, reach the SBC and then move onto the MS Teams cloud, whereupon it would then reach the employee. Very simply: PSTN – SIP Trunk – SBC – MS Teams – Employee.
- A call made by the employee to someone with a cellphone and based in India would first go over MS Teams cloud, get routed to the SBC, onto the SIP Trunk and then onto the TSPs PSTN network. Very simply: Employee – MS Teams – SBC – SIP Trunk – PSTN.
The benefits
For users, the great benefit is that they have a single interface – MS Teams for IP calls and for PSTN. Users get:
- A single interface for multiple interactions – PSTN calls, IP calls, chat, conference, meetings, the works!
- Professional caller ID: The enterprise assigns the user ID, the enterprise controls the contact book, branding, compliance, trust – all are baked in.
- Access all calls on phone, tablet, laptop, desktop – wherever Teams is installed.
- Unified call logs and voicemail.
For the enterprise too, there are many benefits:
- You can define complex dial plans, call restrictions, routing priorities, etc., at the SBC level.
- If you have already invested in SBCs and have an extensive on-prem voice infra, you can extend its life even as you plan out a migration path for the future.
- Future readiness – Using SIP trunks from the TSP is easier to manage, faster to deploy, quick to upgrade – compared with the MPLS or PRI route.
- Less complex – Reduced cost of maintaining multiple voice platforms, simplifying management and monitoring.
- Easier and better reporting – because all the CDR data is available on a single platform.
The caveats:
- The TSP will give you numbers, but no SIM cards! These numbers will work via MS Teams, but Wi-Fi or broadband or a mobile connection – like how a Whatsapp call works. Naturally, all the other capabilities provided by true mobile systems (like emergency calling etc.) are not available.
- Forget number portability. The numbers are allocated by the TSP, not by Microsoft or your company, so if you decide to go to another service, the number goes back to the TSP
- Indian telecom policy requires that PSTN media must stay within India. That means the SBC and TSP interconnect should be India-based.
- You must have (or buy) MS-certified SBC infrastructure. And managing SIP routing, failover, QoS, etc. is your responsibility.
- Also, you need to have licensing in place as well – either a Microsoft E5 License or, if you have Microsoft 365 Licenses, buy Add-on Phone System Standard Licenses.
OSP Compliance: Is Teams DR Legal for Indian Call Centers?
Teams DR, by itself, is just an architecture that improves the customer experience for enterprises. Since it is offered by Airtel, Tata Telecom and Tata Telebusiness, it is perfectly OK for use in unified communication in India.
But what about OSP? Is it OK to use in a call center in India?
The short answer is YES, but carefully.
At its very core, OSP regulation requires the following:
- Media and signaling for Indian PSTN calls must stay within India.
- CDRs and system logs must be available in India.
- No toll bypass must take place.
Yes, I know there’s a ton of nuance to all this, but for the purposes of the Teams DR question, these points are good enough to start with.
Calls made by the employee may bounce around all over the MS Teams cloud but they exit the enterprise via the SBC to the TSP’s network, where they transition over to the PSTN. At no point does this bypass the TSPs toll gates. Also, since these are Indian TSPs, they are both required to and responsible for media and signaling remaining in India when on their networks.
So what do you as an OSP have to deal with?
- CDR and system log storage
- Signaling and Media on MS Teams
Talk with Microsoft, get their assurance that MS Team does not send the signaling and media out of India, and that they can provide the CDRs and system logs for your local storage. Once this is sorted out, you are ready to deploy Teams Direct Routing even in your OSP setup!