mitel
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Mitel
For half a century Mitel has run the office phone. After a 2025 debt reset, the Canadian veteran is betting that hybrid - part on-premises, part cloud, part AI - is where enterprise communication actually lives.
Callab AI
Callab AI builds AI voice agents that plug directly into the legacy, on-premises phone systems most large call centers still run on. Instead of forcing a cloud migration, its carrier-grade telephony stack connects to hardware like Avaya, Cisco UCM, and Mitel over SIP trunks and automates a large share of inbound calls within about a week. Founded by Tunisian engineers Haithem Kchaou and Chehir Dhaouadi and part of Y Combinator's Spring 2026 batch, the company handles calls in Arabic and its dialects plus several other languages, and serves customers across North America, Europe, and the Middle East.
ProTelesis Corporation
ProTelesis Corporation is a San Diego-based managed services provider (MSP/MSSP) born from the 2019 merger of two California telecom heavyweights - Protel (a leading Mitel Blue dealer) and Xtelesis (a leading Mitel Orange dealer). The company has evolved from a traditional phone-system business into a full-stack technology partner delivering managed IT, cybersecurity, unified communications, cloud, structured cabling, and managed detection and response. With offices across California, the Pacific Northwest, Utah, and Bangalore, it supports thousands of clients and hundreds of thousands of endpoints, with a focus on biotech, defense, and growing small-to-midsize businesses.