Part-Time Senior Telephony Infrastructure & Integration Engineer (VoIP / SIP / AI Voice)

Compensation: $40k – $60k • No equity

Location: Remote (Latin America Preferred) Employment Type: Part-Time (Up to 10-20 Hours per Week) Compensation: Hourly **About SkipHold** SkipHold is building the next generation of AI-powered business communications. Our platform enables MSPs, UCaaS providers, telecom providers, and enterprises to seamlessly integrate conversational AI with existing phone systems—allowing AI receptionists, intelligent call routing, live call transfers, WhatsApp voice, SIP infrastructure, and cloud PBXs to work together as one unified communications platform. Our mission is to modernize business telephony without requiring organizations to replace the PBX infrastructure they already own. **About the Role** We're looking for a Senior Telephony Infrastructure & Integration Engineer who enjoys solving complex voice infrastructure challenges. This role sits at the intersection of: Enterprise Telephony SIP Networking Cloud PBXs Linux Infrastructure Carrier Interoperability AI Voice Platforms Cloud Infrastructure Real-Time Communications You'll help build, maintain, test, and optimize the telephony infrastructure powering SkipHold's AI platform while ensuring interoperability across multiple PBX vendors, SIP carriers, AI voice platforms, and cloud communications providers. This is an engineering-focused position—not simply PBX administration. You'll collaborate closely with our software engineering team to validate new telephony features, troubleshoot production issues, build reusable deployment templates, and improve the reliability of our communications platform. **Responsibilities** Deploy, configure, and maintain FusionPBX and FreeSWITCH environments. Configure SIP trunks, gateways, DIDs, extensions, dial plans, and routing logic. Design and troubleshoot inbound and outbound call routing across multiple carrier environments. Build and validate interoperability with supported PBX platforms including FusionPBX, FreePBX, 3CX, Netsapiens, and future supported systems. Configure IVRs, ring groups, call queues, hunt groups, failover routing, and business call flows. Design, test, and troubleshoot blind transfers, warm transfers, attended transfers, SIP REFER, conferencing, and advanced call routing scenarios. Integrate AI voice platforms including Vapi, LiveKit, Retell AI, OpenAI Realtime, ElevenLabs Conversational AI, and future real-time communications platforms. Validate AI-to-human handoff workflows, call summarization, intelligent routing, and conversational voice experiences. Troubleshoot SIP signaling, RTP media flow, NAT traversal, codec negotiation, SIP header normalization, ringback behavior, and call quality issues. Support Ringotel deployments and endpoint provisioning. Configure secure SIP communications using TLS, SRTP, authentication, and industry best practices. Manage Linux-based PBX servers and supporting cloud infrastructure. Configure DNS, SSL certificates, firewall rules, networking, VPNs, and server security. Support infrastructure hosted in DigitalOcean, AWS, Azure, and Google Cloud as required. Configure and maintain Twilio Voice, SIP trunking, BYOC, and carrier integrations. Build reusable deployment templates and standardized PBX configurations. Evaluate and integrate emerging AI voice technologies as the SkipHold platform evolves. Create deployment guides, troubleshooting runbooks, infrastructure documentation, and engineering knowledge articles. Collaborate with software engineers on telephony APIs, automation, infrastructure improvements, and product development. Participate in staging validation, production troubleshooting, release testing, and infrastructure planning. **Required Qualifications** Hands-on experience administering one or more modern IP PBX platforms (FusionPBX preferred). Strong FreeSWITCH experience or equivalent SIP-based telephony platforms. Deep understanding of SIP, RTP, VoIP, enterprise telephony, and call routing. Experience configuring SIP trunks, carriers, gateways, and DID routing. Strong Linux administration experience (Ubuntu/Debian preferred). Experience troubleshooting SIP signaling, RTP media, codec negotiation, NAT traversal, and call quality. Strong networking knowledge including DNS, firewalls, SSL/TLS, VPNs, and routing. Ability to independently diagnose complex telephony infrastructure issues. Strong written documentation and communication skills. Ability to work independently with minimal supervision. **Preferred Qualifications** Experience with one or more of the following: PBX Platforms FusionPBX FreeSWITCH FreePBX 3CX Netsapiens Kamailio OpenSIPS AI Voice Platforms Vapi LiveKit Retell AI OpenAI Realtime API ElevenLabs Conversational AI Twilio Voice BYOC deployments Infrastructure DigitalOcean Amazon Web Services (EC2, VPC, Route 53) Microsoft Azure Google Cloud Platform Docker PostgreSQL Development GitHub REST APIs JSON Postman Bash Python Troubleshooting Wireshark sngrep tcpdump FreeSWITCH CLI SIP tracing RTP analysis Experience supporting MSPs, telecom providers, cloud PBX providers, UCaaS platforms, or carrier-grade voice environments is highly desirable. **Core Technologies** Telephony FusionPBX FreeSWITCH FreePBX 3CX Netsapiens SIP RTP SRTP TLS WebRTC STUN/TURN SIP REFER SIP Trunks BYOC DID Routing IVRs Ring Groups Call Queues Warm Transfers Blind Transfers Attended Transfers Codec Negotiation Carrier Interoperability SIP Header Manipulation AI & Communications Conversational AI AI Receptionists Vapi LiveKit Retell AI OpenAI Realtime API ElevenLabs Conversational AI Human Handoff Real-Time Audio Streaming Intelligent Call Routing Call Summarization Voice Automation Infrastructure Linux Ubuntu Debian DigitalOcean AWS EC2 AWS VPC Route 53 Azure Google Cloud Platform DNS SSL Firewalls NAT VPN Cloud Infrastructure Development GitHub REST APIs JSON PostgreSQL Docker Bash Python Infrastructure Automation Troubleshooting Wireshark sngrep tcpdump SIP Debugging RTP Analysis FreeSWITCH Logs Linux System Logs **What We're Looking For** We're looking for an engineer who enjoys solving difficult infrastructure problems and takes ownership of production reliability. The ideal candidate is equally comfortable working in Linux terminals, reading SIP traces, troubleshooting PBX call flows, collaborating with software engineers, integrating AI voice platforms, and helping build the future of AI-powered business communications. You should be proactive, detail-oriented, curious, and excited about working at the intersection of telecommunications, cloud infrastructure, conversational AI, and enterprise software. If you're passionate about modernizing enterprise communications and building reliable voice infrastructure that powers next-generation AI experiences, we'd love to hear from you