IMS Engineer at Telnyx

Dublin, County Dublin, Ireland

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Not SpecifiedCompensation

Mid-level (3 to 4 years), Senior (5 to 8 years)Experience Level

Full TimeJob Type

UnknownVisa

TelecommunicationsIndustries

Requirements

VoLTE expertise: Hands-on IR.92 (voice/SMS), registration/attach flows, SIP/SDP (AMR-WB/EVS), QoS/bearers via PCRF/PCF, emergency calling, multi-vendor interop
Core IMS/SIP: 5+ years with SIP/IMS; strong grasp of 3GPP (TS 23.228, 24.229, 29.xx), CSCF roles, registration, service routing
Kamailio mastery: Confident authoring kamailio.cfg routing logic; registrar/dialog/topology hiding; IMS modules in production
Software engineering to modify Kamailio (required): Proficient in C for high-performance network services (memory management, concurrency, lock-free/atomic patterns)
Experience building and changing Kamailio core/modules (parsers, transaction/dialog layers, ims_*), adding/adjusting AVPs/headers, and writing new module logic
Tooling: gcc/clang, make, gdb, valgrind/AddressSanitizer, perf/flamegraph, packet tools (pcap, sngrep, ngrep)
Strong unit/functional testing habits; familiarity with Kamailio test approaches and CI
Comfortable proposing and landing upstream PRs, engaging in code review, and maintaining forks/patch sets
Systems & SRE: Linux networking, DNS (NAPTR/SRV), TLS/mTLS, observability (Prometheus/Grafana, ELK/Loki/OpenTelemetry)
Automation: Git workflows, CI/CD, Docker/Kubernetes, IaC (Terraform/Helm), scripting (Python/Bash/Lua)
Communication: Clear design docs and incident write-ups

Responsibilities

Design & build: Own P-/I-/S-CSCF call flows; configure Kamailio modules (ims_*, dispatcher, topos, tm, usrloc, permissions); integrate HSS/UDM/UDR
Productize: Turn prototypes into supportable services with versioned configs, CI/CD, and observability
Performance & scale: Tune throughput, dialog/state handling, NAT traversal, DNS/SRV, TLS/mTLS; benchmark CPS/latency
Reliability: Architect HA/DR; lead load tests, game days, incident reviews
Security: Implement abuse/DoS controls (pike/htable/rate limiters), auth, encryption, and audit-grade logging
Upstream: Contribute fixes/patches and collaborate with the Kamailio community
On-call (shared): Keep the voice core healthy

Skills

Key technologies and capabilities for this role

KamailioIMSP-CSCFI-CSCFS-CSCFVoLTEHSSUDMUDRCI/CDDNS/SRVTLS/mTLSHA/DR

Questions & Answers

Common questions about this position

What are the must-have skills for the IMS Engineer role?

Candidates must have VoLTE expertise including hands-on IR.92, Core IMS/SIP with 5+ years experience and strong grasp of 3GPP standards, Kamailio mastery for configuring routing logic and IMS modules in production, and software engineering proficiency in C to modify Kamailio core and modules.

Is remote work available for this position?

This information is not specified in the job description.

What is the salary or compensation for the IMS Engineer role?

This information is not specified in the job description.

What does the company culture at Telnyx look like?

Telnyx fosters an environment of continuous learning and growth, driven by a desire to transform antiquated systems through innovative connectivity solutions, with a collective vision for borderless connectivity fueling limitless innovation.

What makes a strong candidate for this IMS Engineer position?

A strong candidate will have hands-on VoLTE expertise, 5+ years in Core IMS/SIP with deep 3GPP knowledge, proven Kamailio mastery in production, and required proficiency in C programming to build and modify Kamailio modules, along with experience in performance tooling like gcc, gdb, and perf.

Telnyx

Provides cloud-based communication services

About Telnyx

Telnyx provides communication services over the internet, focusing on voice, messaging, wireless, and fax services for businesses. Its self-service platform, the Mission Control Portal, allows clients to manage their communication needs, such as phone numbers and messaging, in one place. The company operates on a pay-as-you-go pricing model, charging clients based on their usage of services like voice calls and text messages. Telnyx stands out from competitors by owning its global IP network, which enhances service reliability and security. The company's goal is to deliver high-quality communication solutions that are both cost-effective and dependable for businesses of all sizes.

Chicago, IllinoisHeadquarters

2009Year Founded

$972.7KTotal Funding

SEEDCompany Stage

Enterprise Software, CybersecurityIndustries

201-500Employees

Benefits

Health Insurance

401(k) Company Match

401(k) Retirement Plan

Unlimited Paid Time Off

Share Options

Risks

Breaches of anti-scam rules could harm Telnyx's reputation and finances.

Increased competition from AI-driven platforms may erode market share.

Past DDoS attacks highlight potential network security vulnerabilities.

Differentiation

Telnyx offers a cloud-agnostic IP network for carrier-grade communication services.

The Mission Control Portal provides a self-service platform for managing communication needs.

Telnyx's global IP network ensures high performance and control over services.

Upsides

Partnership with LivePerson enhances AI-driven customer engagement solutions.

Launch of Global Edge Router boosts network capabilities for enterprise clients.

Voice AI introduction positions Telnyx in the growing AI voice communications market.

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