Asterisk / SIP / Cisco Telephony Administrator

Who are we looking for

We are seeking an experienced Asterisk SIP & Cisco Telephony Administrator (part-time contractor) with strong expertise in VoIP telephony systems, call routing, IVR design, SIP protocols, Cisco call center/telephony tools, and integrations with enterprise call center platforms. You will be responsible for maintaining, optimizing, and extending our telephony infrastructure to ensure maximum uptime, high quality of service, and seamless communication across the organization.

Required skills and experience

• 3+ years of hands-on experience with Asterisk (FreePBX/Issabel acceptable, but deep Asterisk knowledge required).
• Direct experience with Cisco telephony (CUCM, CUBE, SIP gateways, UCCX/UCCE).
• Strong understanding of SIP protocol, call flows, codecs, RTP/RTCP.
• Solid experience with dial plans, AGI/ARI, queues, IVR, and call routing.
• Familiarity with Linux administration (Debian/Ubuntu/CentOS).
• Experience integrating telephony with external systems using APIs or middleware.
• Understanding of VoIP networking (VLANs, QoS, NAT, firewalls, SBCs).
• Knowledge of call center operations, KPIs, reporting, and call handling strategy.

Nice to have

• Experience with Kamailio/OpenSIPS for SIP proxying.
• Experience with WebRTC and SIP over WebSocket.
• Familiarity with cloud telephony platforms (AWS Chime, Twilio).
• Experience with hybrid Cisco–Asterisk environments.

Key Responsibilities

Asterisk & SIP Administration

• Configure, manage, and troubleshoot Asterisk PBX systems (SIP, PJSIP, DAHDI, AMI/ARI).
• Implement routing logic, dial plans, call queues, call forwarding, and failover scenarios.
• Maintain SIP trunks and providers (TCP/UDP/TLS/SRTP).
• Ensure system uptime, performance tuning, call quality monitoring (QoS, jitter, latency, MOS).

Cisco Telephony / Call Center Systems

• Configure and maintain Cisco Unified Communications Manager (CUCM), Cisco CUBE, Cisco SIP Gateways, and Cisco Contact Center (UCCX/UCCE) components.
• Troubleshoot interoperability issues between Cisco and Asterisk, including SIP normalization, dial plan alignment, codecs, and media routing.
• Manage Cisco voice routing, SIP trunks, SRST, and redundancy configurations.
• Apply Cisco best practices for VoIP security, QoS, VLAN segmentation, and failover.

Call Center Systems Integration

• Integrate Asterisk and Cisco telephony systems with CRM/Helpdesk/Call Center platforms (e.g., Cisco CCX, Genesys, Zendesk, Avaya, custom CRM).
• Develop and maintain API-based integrations (REST, Webhooks, AMI/ARI events).
• Work with call center reporting/analytics tools (CDR, queue logs, call recordings).

Telephony Infrastructure & Networking

• Configure SIP proxies, SBCs, NAT traversal (STUN/TURN/ICE), and SIP security.
• Manage RTP flows, media servers, and transcoding (G.711, G.729, Opus, GSM).
• Configure and troubleshoot Cisco SBC/CUBE, SIP normalization profiles, and dial-peer routing.
• Implement high availability, redundancy, and load-balancing for telephony services.

Monitoring & Security

• Maintain logging/monitoring tools (Grafana, Prometheus, Asterisk logs, sngrep, Homer/HEP).
• Ensure VoIP security: SIP authentication, firewall rules, intrusion prevention, and anti-fraud.
• Maintain backup/restore processes for configurations, prompts, and call recordings.