Role: Senior Core Telephony / SIP Integration Engineer

Location: Mountain View, CA (In-Office)

Our client is a frontier AI company building ethical AI infrastructure for voice generation and deepfake detection. Backed by $23M from strategic investors including Google, Sony, Okta, and In-Q-Tel (CIA), they serve government agencies, Fortune 500 companies, and law enforcement. Their mission is to ensure trust and authenticity in the generative AI era.

With dual capabilities in AI voice generation and detection, they hold a defensible position in an emerging category with no established standards. Major public deployments are planned for 2026, making this a critical moment for category-defining product leadership.

Position Overview:

The Senior Core Telephony / SIP Integration Engineer will own low-level telephony integrations end-to-end, focusing on carrier-grade SIP and RTP workflows. Reporting to senior technical leadership, this role blends telephony infrastructure problem-solving, protocol-level debugging, and direct collaboration with enterprise customer engineering teams.

This is a hands-on, deeply specialized role operating below typical VoIP abstractions, directly interacting with SIP INVITEs, RTP streams, FreeSWITCH, and Session Border Controllers (SBCs). The engineer ensures that complex telco integrations are reliable, repeatable, and secure.

Key Responsibilities:

• Receive and handle SIP INVITEs from external enterprise and telco systems
• Process RTP audio streams in real-time
• Configure and extend FreeSWITCH for monitoring and compliance use cases
• Support one-call and two-call monitoring setups (inbound/outbound streams)
• Route calls using destination numbers and SIP headers
• Attach and interpret metadata via custom SIP headers
• Debug SIP signaling, call flows, and RTP behavior
• Work closely with a Python backend running locally on-premises
• Collaborate directly with customer engineering teams
• Ensure reliable operation in security-sensitive, on-prem environments

Qualifications:

✅ You likely fit if you:

• Have 5+ years of hands-on experience in carrier-grade telephony engineering
• Are highly skilled in SIP at the protocol level, RTP, call flows, and headers
• Have experience with Session Border Controllers (SBCs) and FreeSWITCH configuration
• Understand real-world SIPREC implementations and telco system quirks
• Have operated in telco or regulated enterprise environments
• Are comfortable debugging complex telephony systems with packet captures
• Can work below typical VoIP abstractions to solve infrastructure problems
• Have experience integrating Python services alongside telephony systems (nice-to-have)
• Thrive in fast-moving, ambiguous environments
• Can commit to collaborating with enterprise customers to deliver production-ready solutions

❌ This role is not for you if:

• Only have experience with high-level VoIP APIs (e.g., Twilio)
• Avoid protocol-level debugging
• Prefer clean, textbook standards over messy real-world systems
• Are looking for a general backend or product engineering role

What they offer:

• Competitive compensation
• Direct collaboration with senior technical leadership
• Hands-on, high-impact role in a pioneering AI voice security company
• Clear path for growth into leadership roles in engineering and infrastructure

Interested?

If you’re reading this thinking “this is exactly me”, please DM me on LinkedIn!🔗