Telco Testing & Monitoring Engineer at Holafly in Lisbon, Portugal

Company Overview

Holafly is a high-growth scale-up revolutionising how businesses and travellers connect to the internet abroad. Since 2018, we’ve empowered travellers in over 200 destinations worldwide with secure and reliable eSIM solutions. With a team of 800+ professionals across multiple countries, we are scaling globally to support travellers with seamless, unlimited data connectivity.

We’re not just connecting people—we’re enabling freedom and peace of mind, ensuring our users stay connected from the second they land, wherever their journey takes them.

The Role

As a Telecommunications Testing & Monitoring Engineer, you will be responsible for establishing and operating the technical testing and monitoring framework used to measure, validate, and continuously improve connectivity across our global mobile network footprint.

Key Responsibilities

• Own and operate network testing and monitoring platforms, including SIGOS/Mobileum or similar tools, covering test SIM setup, campaign configuration, scheduling, reporting, and continuous monitoring.
• Design and execute automated, manual, and IREG testing across global operators for 2G, 3G, 4G/LTE, 5G NSA/SA, new roaming partners, IMSIs, interconnections, and service launches.
• Perform hands-on troubleshooting and root cause analysis using signalling traces, packet captures, monitoring data, and protocols such as MAP/SS7, Diameter, GTP, DNS and GRX/IPX.
• Validate roaming, eSIM, and multi-IMSI behaviour, including IMSI selection, network selection, profile behaviour, roaming accessibility, service availability, and go-live readiness.
• Drive proactive network assurance and performance improvement by building alerts, maintaining testing documentation and operator history, supporting Carrier/Network Operations, and turning technical results into insights for SLA reviews and partner discussions.

Qualifications

• Proven experience in Mobile Telecommunications, ideally across Network Engineering, Roaming, NOC, Service Assurance, Testing, IREG, or Service Delivery.
• Strong hands-on expertise with SIGOS/Mobileum or equivalent roaming testing platforms, including test SIM configuration, test cases, automated campaigns, scheduling, and reporting.
• Practical experience with IREG and international roaming testing, including new operator onboarding, service acceptance, and validation across 3G, LTE, and 5G networks.
• Good understanding of mobile roaming architecture and eSIM technologies, including SM-DP+, eSIM profiles, multi-IMSI, and network selection behaviour.
• Strong troubleshooting skills with the ability to analyse network traces, signalling messages, test results, and monitoring data to identify service degradation and root causes.
• Experience operating telecom monitoring/service assurance tools, combined with strong communication skills to work effectively with engineering teams, roaming partners, carriers, and technology vendors.

Nice-to-haves

• Knowledge of GRX/IPX, VPLMN/HPLMN architectures and GSMA roaming procedures, including IR.21, IR.24, IR.38 and IR.35.
• Experience with Wireshark and signalling trace analysis for troubleshooting roaming and network issues.
• Familiarity with monitoring dashboards, KPI/alerting frameworks, carrier SLAs, roaming agreements and operator performance management.

Benefits & Perks

• Remote-first culture with a focus on outcome over hours.
• Flexible working schedule to support your work-life balance.
• The opportunity to grow within a blameless, collaborative environment that values ownership and continuous improvement.