Asterisk / SIP / Cisco Telephony Administrator

Isa Cybersecurity Inc.; San Francisco (CA); On-site; USD 68,880 - 96,432; Part time

Job summary

Isa Cybersecurity Inc. is seeking an experienced Asterisk SIP & Cisco Telephony Administrator (part-time contractor) in San Francisco, California. The role involves expertise in VoIP telephony systems and Cisco tools to optimize telephony infrastructure and ensure high communication quality.

Candidates should have a robust understanding of SIP protocols, call routing, and be proficient in configuring Asterisk PBX systems. This position supports seamless communication and reliability across the organization.

Qualifications

• 3+ years of experience with Asterisk, preferably in VoIP.
• Direct experience with Cisco telephony components (CUCM, CUBE).
• Strong understanding of SIP protocols and call routing.

Responsibilities

• Configure and manage Asterisk PBX systems for optimal performance.
• Integrate Asterisk with CRM/Helpdesk systems for call center operations.
• Maintain VoIP security, ensuring reliable communications.

Skills

Asterisk

Cisco Telephony

SIP Protocol

VoIP Networking

Linux Administration

Tools

Cisco Unified Communications Manager (CUCM)

Asterisk PBX

Grafana

Prometheus

Job description

Asterisk / SIP / Cisco Telephony Administrator

Europe

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

• 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).
• 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.