About the Client
The clients included a US-based telecom startup aiming to modernize landline calling via mobile VoIP, a telecom R&D firm specializing in voice continuity between CS and IMS networks, and a North American startup seeking funding with a robust SIP softphone demo. Each client sought scalable VoIP solutions that combined mobile development, backend SIP server integration, and advanced telecom protocol support.
Industry
Telecommunications | Mobile App Development | High-Tech | VoIP & IMS Integration
Project Title
Unified Case Study: Multi-Project VoIP Product Development & Integration Across Mobile, PSTN & IMS Networks
Scope
- Build cross-platform VoIP client apps for Android & iOS
- Integrate PSTN landline access via SLIC hardware
- Develop a SIP-based softphone app with call continuity, conferencing, and transfers
- Engineer seamless handover between CS (circuit-switched) and IMS networks
- Deploy and manage SIP backend (Asterisk, FreeSWITCH, Kamailio)
- Provide firmware-level integration with hardwar.
- Support NAT traversal and background execution for persistent mobile calling
- Deliver investor-ready MVPs and high-quality PoCs under compressed timelines
Challenges
- 📱 Real-time PSTN-to-Mobile VoIP bridging using SIP over unstable networks
- 🔄 Seamless handover logic between cellular and IP networks with <150ms transition time
- 🕒 Aggressive 6-week PoC delivery timeline ahead of VC funding round
- 🔐 Secure SIP registration, session management, and NAT traversal
- ⚙️ Integration with third-party hardware (SLIC card, device) and proprietary systems
- 🔋 Maintain persistent SIP connectivity in sleep mode across iOS and Android
- 🎯 Achieve carrier-grade performance and beta stability across devices
Solutions
✅ Mobile App Development
- Native iOS (Swift) and Android (Kotlin/Java) apps with SIP VoIP functionality
- Used PJSIP and Linphone SDKs to deliver real-time communication
- Enabled key call features: dialing, receiving, transfers, conferencing, and DTMF
- Persistent background SIP execution with low dropped-call rate
✅ VoIP Backend & Infrastructure
- Deployed Asterisk, Kamailio, and FreeSWITCH for backend SIP handling
- Configured STUN/TURN servers to address NAT traversal
- Integrated PSTN via SLIC-enabled device and SIP gateway
- Scalable AWS EC2-based hosting and DevOps automation via Jenkins & GitHub Actions
✅ Hardware Integration
- Firmware support for proprietary SLIC-enabled telecom device
- Secure handshakes and registration flows from app to hardware via SIP signaling
✅ Call Continuity (VCC) Development
- Developed VCC logic to enable fixed-mobile convergence
- Built SIP-based dynamic call handoff engine with 3GPP TS23.206 compliance
- Conducted interoperability and voice quality testing across IMS networks
✅ Agile Delivery and Support
- Adopted Agile sprint planning and CI/CD pipeline for real-time adaptability
- Weekly demos, Jira-based tracking, and transparent communication with clients
- Offered post-MVP support including scaling, monitoring, and roadmap alignment
Tech Stack Used
Mobile Platforms:
- Java (Android), Kotlin, Swift (iOS), Objective-C
VoIP/SIP Libraries:
- PJSIP, Linphone SDK
Server & Infrastructure:
- Asterisk, Kamailio, FreeSWITCH, AWS EC2, Docker, Jenkins, GitHub Actions, NGINX
Hardware:
- Device, SLIC Card
Protocols & Standards:
- SIP, RTP/RTCP, SDP, DTMF, WebRTC, STUN/TURN, ICE
- 3GPP TS23.206 Stage 2 Release 7 (for VCC compliance)
Suventure’s Role as Strategic Partner
👨💻 End-to-End Product Development
- Designed, developed, and tested mobile apps and SIP stack integration
- Engineered firmware compatibility and real-time VoIP functionality
🔍 Telecom & Backend Engineering
- Configured and optimized SIP infrastructure for low-latency voice handling
- Delivered feature-rich telecom modules using industry-standard protocols
🛠️ DevOps & QA
- Implemented CI/CD pipelines, testing frameworks, and performance monitoring
- Conducted interoperability testing with telecom networks and IMS systems
💼 Client Enablement
- Helped secure VC funding with rapid MVP development
- Provided ongoing roadmap support for scaling into enterprise solutions
Results Achieved
📞 28% Reduction in Call Latency via optimized SIP routing
📱 >92% Call Success Rate across Wi-Fi/3G/4G during beta testing
🧪 99.8% Crash-Free Sessions across Android and iOS platforms
⏱️ 6 Weeks to PoC Delivery ahead of high-stakes VC showcase
💵 40% Cost Savings through offshore development and agile execution
📶 100% Call Handover Success Rate in VCC prototype lab tests
📲 >90% End-User Success Rate for landline-to-smartphone VoIP functionality
🚀 $1.5M VC Funding Secured post MVP demo
🤝 Retained for Long-Term Product Scaling & Telecom Integrations
Client Testimonials
“Suventure helped us turn our product vision into a reliable, scalable VoIP solution. Their full-stack team and agile delivery model made it possible to go live in record time.”
— Product Head, US-Based Telecom Startup
“We needed a partner who could quickly deliver a robust, feature-rich SIP phone application while helping us prepare for a VC showcase. Suventure delivered beyond our expectations.”
— Founder & CEO
“Suventure’s VCC prototype showcased our vision for fixed-mobile convergence. Their deep telecom stack expertise ensured success from design to deployment.”
— Head of Product Engineering,