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Connect Microsoft Teams Phone to PSTN through SIPPER's Ribbon SBC and Pure VoIP Network. Keep your Thai phone numbers, avoid per-user Calling Plan fees, and get enterprise-grade voice quality for Teams calls.
Overview
Direct Routing lets you connect Microsoft Teams Phone to your own PSTN carrier instead of purchasing Microsoft Calling Plans. SIPPER provides a Microsoft-certified Ribbon SBC SWe Edge, SIP Trunk over our Pure VoIP Network with direct NT (National Telecom) and True Corporation interconnection, and Thai DID numbers — so Teams users can make and receive real phone calls with enterprise-grade quality.
Microsoft-certified Ribbon SBC SWe Edge managed by SIPPER — supports up to 2,000 concurrent sessions with 1:1 active-standby HA and mid-call failover. Handles SIP-to-Teams protocol conversion, media transcoding, topology hiding, and DoS/DDoS protection.
Calls route through SIPPER's Pure VoIP Network — dedicated voice-only infrastructure with no mixed traffic. Direct interconnection with NT (National Telecom) and True Corporation carriers. Thai DID numbers included with bundled calling credit.
Port your existing Thai phone numbers to SIPPER. We coordinate with NT and True carriers end-to-end — most ports complete within 5-10 business days. No number changes for your customers, partners, or employees.
Key Features
Microsoft Calling Plans charge per user per month. Direct Routing uses concurrent channels instead — pay for capacity, not headcount. Typically 30-50% savings for organizations with 50+ users compared to Microsoft Calling Plans.
Local DID numbers in Bangkok and regional areas via NT and True carrier interconnection. Port existing numbers or provision new ones. Full CLI pass-through and Flexible Caller ID — including Mobile CLI for higher answer rates on outbound calls.
TLS for signaling, SRTP for media via SDES key exchange. Ribbon SBC adds topology hiding (B2BUA), DoS/DDoS protection, rate limiting, and rogue RTP filtering — enterprise-grade security from Teams client to carrier network.
1:1 active-standby Ribbon SBC SWe Edge pair supporting up to 2,000 concurrent sessions. Mid-call failover preserves active calls during hardware failure. Multi-carrier failover with NT and True. 99.99% SLA.
Run Direct Routing alongside your existing PBX. Some users on Teams, others on Yeastar or 3CX — sharing the same SIP Trunk and DID numbers through the Ribbon SBC. Migrate users gradually at your own pace.
When enabled, media flows directly between Teams client and SIPPER SBC — bypassing Microsoft cloud for lower latency and better voice quality. Especially beneficial for users in Thailand connecting to local PSTN numbers.
Who is this for
Direct Routing is the preferred PSTN connectivity method for organizations that want control over their voice infrastructure and costs.
You have Microsoft 365 E5 (or E3 + Phone System add-on) and want to add PSTN calling without Microsoft Calling Plans. Direct Routing gives you more control and typically lower cost.
Moving from an on-premise PBX to Teams for calling and collaboration. SIPPER handles the voice connectivity side so you can focus on the Teams rollout.
Organizations with offices across Thailand or internationally. Centralize voice infrastructure through one SBC and trunk, with local DID numbers in each region.
Full Capabilities
How It Works
SIPPER handles all the infrastructure. You just need Microsoft 365 with Phone System license — we take care of the SBC, trunk, and carrier connectivity.
We provision a dedicated Ribbon SBC SWe Edge instance for your tenant with 1:1 active-standby HA. The SBC is paired with Microsoft Teams in your Microsoft 365 admin portal. SIPPER handles all configuration including TLS certificates, SIP profiles, codec settings (G.711/G.722/G.729/Opus), security policies, and topology hiding.
Choose new Thai DID numbers or port your existing numbers from your current provider. Numbers are provisioned via our direct NT and True carrier interconnection and configured on the SBC. SIPPER manages the carrier-side porting process end-to-end — most ports complete within 5-10 business days.
Phone numbers are assigned to Teams users in the Microsoft 365 admin center. Users can immediately make and receive PSTN calls from their Teams desktop, mobile, or web client. SIPPER configures Auto Attendants, Call Queues, and Resource Accounts as needed. 24/7 NOC monitors call quality from day one.
No need to move all users to Teams at once. SIPPER's Ribbon SBC can route calls to both Teams and your existing PBX (Yeastar, 3CX, Asterisk, or legacy systems) through the same SIP Trunk. Shared DID numbers let you migrate users gradually — some on Teams, some on PBX — while maintaining a single voice infrastructure and phone number pool.
FAQ
You need Microsoft 365 E5 (which includes Phone System) or Microsoft 365 E3 plus the Phone System add-on. You do NOT need Microsoft Calling Plans — Direct Routing replaces them with SIPPER's SIP Trunk.
Microsoft Calling Plans are a per-user monthly fee where Microsoft acts as your phone carrier. Direct Routing lets you choose your own carrier (SIPPER) and use concurrent channels instead of per-user pricing. This typically costs less for organizations with 50+ users and gives you more control over your voice infrastructure.
No. SIPPER provides and manages the Ribbon SBC as a service. You do not need to purchase, host, or maintain any SBC hardware or software. The SBC is included in the Direct Routing service.
Yes. SIPPER handles number porting from your current provider. Most ports complete within 5-10 business days with minimal disruption. Your customers and partners continue calling the same numbers.
Yes. SIPPER supports hybrid deployments where some users are on Teams and others are on Yeastar or 3CX PBX. Both platforms share the same SIP Trunk and phone numbers through the Ribbon SBC.
Calls route through SIPPER's Pure VoIP Network — a dedicated voice-only network with direct NT and True carrier interconnection and no mixed traffic. The Ribbon SBC supports G.711, G.722 (wideband HD), G.729, and Opus codecs with GPU-accelerated transcoding. Combined with mid-call failover and 24/7 NOC monitoring, this delivers enterprise-grade quality.
Media Bypass lets voice media flow directly between your Teams clients and SIPPER's SBC — bypassing Microsoft's cloud media processors. This reduces latency and improves voice quality, especially for users in Thailand calling local numbers. SIPPER configures Media Bypass as part of the Direct Routing setup when your network topology supports it.
Operator Connect is a Microsoft-managed marketplace where carriers connect to Teams through Microsoft's infrastructure. Direct Routing connects your SBC directly to Teams — giving you more control over routing, failover, and hybrid PBX scenarios. SIPPER uses Direct Routing because it supports hybrid PBX+Teams deployments, custom call flows, and our own carrier interconnection for optimal call quality in Thailand.
Get Started
Tell us about your Microsoft 365 setup, number of users, and current phone system. We will design a Direct Routing solution that fits your organization.