Backend Developer / Telecom Integration Engineer

💡 About Us Yesim is an international eSIM provider with 7+ years of experience in delivering secure, seamless connectivity anywhere in 200 countries around the world. We specialize in fast, secure, and global connectivity through advanced eSIM mobile solutions for 3+ million active users. Our innovative app allows to manage multiple eSiMs within a single account - allowing users to effortlessly juggle several plans and share connectivity.

✨ About the Role We are looking for a Backend Developer to develop and maintain the company's telecom infrastructure. The primary focus of this role - integrations with external telecom providers, virtual number services, and voice communication platforms, while ensuring the reliable operation of the entire interaction chain between our products and partner platforms. We are looking for a self-driven engineer who can take technical ownership of the telecom domain: maintain the existing infrastructure, quickly identify and resolve service issues, collaborate with external vendors, and continuously propose architectural improvements as the product evolves.

📝 Responsibilities

• Develop and maintain integrations with telecom vendors and network operators.
• Integrate virtual number services, inbound and outbound calling, call forwarding, and call routing.
• Work with telecom providers' APIs, webhooks, and communication protocols.Support virtual number provisioning, activation, renewal, and deactivation processes.
• Develop business logic for call management, call statuses, billing, and usage limits.
• Handle errors and edge cases originating from external telecom providers.
• Monitor service availability, connection quality, and key technical metrics.
• Investigate incidents and work directly with vendors' technical teams.
• Integrate new telecom providers and standardize their APIs within the overall platform architecture.
• Create and maintain technical documentation.

📩 Requirements

• Strong PHP knowledge (the primary backend language used in the project).
• Solid experience with MySQL, including schema design, query optimization, and stored procedures.
• Backend development experience, including building integrations with external APIs.
• Good understanding of REST APIs, webhooks, message queues, and asynchronous data processing.
• Experience working with high-load or highly available systems.
• Experience with logging, monitoring, and troubleshooting distributed systems.
• Ability to independently work with third-party technical documentation and deliver stable production-ready integrations.
• Experience communicating with technical support teams and engineering teams of external partners.

🌟 Nice to Have

• Experience in the telecom, VoIP, or CPaaS industry.
• Knowledge of SIP, RTP, WebRTC, and call routing principles.
• Experience integrating virtual number platforms, SMS providers, and voice service providers.
• Understanding of telecom billing principles and CDR (Call Detail Record) processing.
• Hands-on experience with Twilio, Vonage, Telnyx, Plivo, DIDWW, or similar platforms.
• Knowledge of international phone number regulations, KYC requirements, and local telecom compliance constraints.

🌍 Languages

• Russian (fluent)
• English (C1)

🎁 What We Offer

• Fully remote work environment.
• Opportunity to work with live product data.
• Rapidly growing product and team.
• Freedom to test and launch new hypotheses.
• Dynamic collaboration across product and engineering teams.

Apply now — join Yesim!