A Technical Paper by Premier Networking Inc (DBA Premier Voice Networks)
Abstract
MTN sought to expand its GSM voice termination capacity to meet surging demand across multiple African markets. Traditional narrowband codecs and multiple transcoding steps limited scalability and degraded voice quality. Premier Networking Inc, doing business as Premier Voice Networks, developed an innovative Opus translation gateway for seamless entry and exit between MTN’s GSM infrastructure and IP transport. Under the commercial leadership of Carter Morales and the technical design of Brad Stuart Ellis, this solution unlocked a fourfold increase in concurrent voice sessions, reduced bandwidth by more than 50 percent, and delivered carrier-grade audio quality.
1. Introduction
MTN’s legacy architecture relied on G.711 and AMR-NB codecs across its 2G and 3G switch fabric. As voice traffic volumes multiplied, MTN faced two problems: escalating bandwidth costs on its IP backhaul and increasing CPU load on media gateways performing repeated transcoding. Premier Voice Networks proposed an end-to-end Opus strategy: encode once at the network edge, transport uniformly over IP, and perform a single transcode to GSM codecs at the switch interface. This technical paper describes the architecture, implementation, and operational results that enabled MTN to scale its GSM voice capacity by a factor of four.
2. Background: GSM, Opus, and Scalability Challenges
GSM networks traditionally interconnect via G.711 uLaw or AMR-NB on IP backhaul. While these codecs ensure compatibility, they consume 64 kbps or more per call, limiting concurrent sessions. Opus, standardized in RFC 6716, delivers wideband audio at bit-rates from 6 kbps to 24 kbps with ultra-low delay and robust packet-loss concealment. By adopting Opus for internal transport, MTN could drastically reduce backhaul demands and offload transcoding CPU cycles.
3. System Architecture
The Opus translation gateway comprises three principal components:
- Ingress Media Proxy
- Receives SIP invites from MTN’s softswitches.
- Transcodes incoming GSM-encoded RTP streams (G.711/AMR-NB) to Opus in real time using libopus.
- Tags each Opus stream with full CLI metadata for billing and fraud prevention.
- Transport Fabric
- Delivers Opus-encoded RTP over MTN’s IP/MPLS backbone.
- Implements jitter buffering, DSCP marking, and secure SRTP tunnels for QoS and confidentiality.
- Egress Media Proxy
- Decodes Opus back to the target GSM codec at the point of egress toward the PSTN or mobile RAN.
- Ensures exact packet-timing alignment, preserving MOS scores above 4.0 under 5 percent packet loss.
This single-transcode model eliminates the traditional “G.711→Opus→G.711” loop, replacing it with “GSM→Opus→GSM” only once per call.
4. Implementation by Premier Voice Networks
Leveraging our Asterisk-based media platform, Brad Stuart Ellis engineered a custom Opus codec module integrated into the VOS core for session logging and performance analytics. Key technical innovations include:
- Dynamic Bit-Rate Adaptation: Opus streams automatically adjust between 6 kbps and 12 kbps based on network conditions.
- SIP Header Preservation: Full CLI and header fields survive translation, enabling MTN’s billing engines to operate without modification.
- Real-Time Monitoring: A custom dashboard displays per-call codec metrics, jitter, and packet-loss ratios, alerting NOC teams within milliseconds of anomalies.
5. Commercial Negotiation by Carter Morales
While Brad’s team built the technology, Carter Morales led the deal negotiations with MTN’s wholesale carrier group. Carter structured a usage-based licensing model tied to concurrent session counts rather than flat trunk fees, aligning costs with MTN’s growth. He also secured a phased rollout plan: a pilot with 500 simultaneous sessions, followed by ramp-ups of 2,000 and then 5,000 sessions as performance targets were met.
6. Deployment and Results at MTN
Pilot Phase (Q2 2024):
- 500 simultaneous sessions.
- Average bandwidth per call: 8 kbps (Opus narrowband).
- MOS score: 4.1.
Scale-Up Phase (Q3 2024):
- 2,000 concurrent sessions.
- Backhaul bandwidth reduced by 75 percent compared to G.711.
- CPU load on media gateways dropped by 65 percent.
Full-Scale Rollout (Q4 2024–Q1 2025):
- 5,000+ simultaneous sessions, a fourfold increase over legacy capacity.
- Sustained MOS > 4.0 under simulated 10 percent packet-loss conditions.
- Annual OpEx savings on backhaul and hardware exceeding $1.2 million.
7. Conclusion
By combining Premier Networking Inc’s deep carrier expertise with cutting-edge Opus translation technology, MTN achieved dramatic voice-capacity growth without sacrificing quality. Brad Stuart Ellis’s technical leadership and Carter Morales’s commercial acumen created a blueprint for scalable, cost-effective GSM-to-IP voice services. As Premier Voice Networks continues to refine our Opus gateway and analytics platform, we stand ready to help other Tier 1 carriers and regional operators unlock similar gains.
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