Telephony Engineer Jobs in California (NOW HIRING)

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What We're Looking For
We are seeking an experienced Cellular Audio Telephony Certification Engineer to lead audio quality validation and certification activities for mobile/cellular devices. The ideal candidate will bring deep expertise in acoustic testing methodologies, hands-on proficiency with HEAD Acoustics measurement systems, and demonstrated experience using Rohde & Schwarz (R&S) network simulators for LTE/VoLTE call testing. This role is critical to ensuring devices meet carrier acceptance criteria, 3GPP specifications, and global regulatory standards

Key Responsibilities:

Audio Certification & Compliance Testing

• Plan, execute, and analyze end-to-end audio telephony tests for cellular devices across LTE, VoLTE, VoNR (5G), VoWiFi, and legacy 2G/3G voice technologies
• Perform acoustic measurements including SLR, RLR, STMR, sidetone, echo loss (TCLw), send/receive frequency response, jitter buffer management, and speech quality (POLQA/P.863)
• Execute certification test campaigns aligned with 3GPP TS 26.131/26.132, GCF, PTCRB, GSMA TS.27, and carrier-specific requirements (e.g., Verizon, AT&T, T-Mobile, Vodafone, NTT DOCOMO)
• Validate devices in handset, handsfree, headset, and speakerphone modes per applicable use cases

Test System Operation & Development

• Configure and operate HEAD Acoustics ACQUA software with hardware such as HMS II.3, labCORE, HEC 03.1, HAE-BT, and artificial ears/mouths for acoustic testing
• Set up and drive Rohde & Schwarz CMW500 / CMX500 / CMW-KM network simulators to emulate LTE/VoLTE/VoNR call scenarios, IMS registration, and codec negotiation (AMR-NB, AMR-WB, EVS)
• Develop automated test scripts and sequences in ACQUA and integrate with R&S CMW for repeatable regression testing
• Maintain calibration integrity of acoustic chambers, artificial heads, and reference equipment

Analysis, Debug & Reporting

• Perform root cause analysis on audio impairments (clipping, distortion, packet loss artifacts, echo, latency, DTX/CNG issues)
• Collaborate with firmware, DSP, and RF teams to debug codec, AEC, noise suppression, and beamforming implementations
• Generate certification-ready test reports, waivers, and compliance matrices for submission to carriers and certification bodies
• Support field trials and IOT (interoperability testing) with live networks

Cross-Functional Leadership

• Serve as the audio SME during design reviews, test plan development, and lab readiness assessments
• Mentor junior engineers on acoustic measurement fundamentals and cellular voice architecture
• Interface directly with certification labs, carriers, and equipment vendors

Syntronic provides our customers a complete portfolio of professional services to support their product development including research & development, new product introduction, manufacturing and aftermarket services. We adopt the latest technologies in electronics design and software development with a pool of technically skilled staff around the world. Among our customers and partners are some of the world’s most technically-intensive businesses and organizations. This pushes us forward in designing to satisfy our customers’ needs with a focus on quality, competence, capacity and continuity.

Syntronic has today over 2000 employees in 8 countries.

Syntronic values diversity in the workplace. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, disability or protected veteran status. If you require accommodation due to a disability at any time during the recruitment and/or assessment process, please contact our recruiting team and we will make all reasonable efforts to accommodate your request.