S

Sipwise

Designs and deploys carrier-grade VoIP platforms

Backend Software Engineer

Full-Time
€53.2k - €67.2k/yr
Mid
Vienna, Austria
Hybrid
Software EngineeringBackend Engineering

About the job

Requirements
  • A minimum of 3 years of experience in software development.
  • Experience with REST API backends, microservices, JavaScript and TypeScript, SQL databases (particularly MariaDB or MySQL), Git, and code-review-driven development.
Responsibilities
  • Implement and integrate new features, and apply design and performance optimizations to the REST API backend and related NGCP modules.
  • Work on various projects, new and existing features, and components.
  • Develop and maintain microservices.
  • Write validation tests and documentation for implemented features.
  • Maintain and improve the MariaDB database model.
Desired Qualifications
  • Experience with Linux operating systems, particularly Debian or Ubuntu.
  • Experience with NestJS, Node.js, and object-relational mapping (ORM).
  • Experience with Redis or similar NoSQL databases.
  • Familiarity with highly available and highly loaded server systems.
  • Experience with other programming languages, including Python and C.
  • Experience with continuous delivery and integration.

About the company

S

Sipwise

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Website

Sipwise designs and delivers carrier-grade VoIP platforms and unified communications solutions for telecom operators, ISPs, and businesses. Its offerings include Class 5 soft switches, Cloud PBX, mobile VoIP clients, and WebRTC-based solutions that cover voice, video, presence, messaging, and more. The products are designed to be scalable, cost-efficient, and easy to integrate with existing networks, enabling operators and service providers to deploy and manage voice and UC services for both SMEs and large enterprises. Sipwise differentiates itself through a focus on carrier-grade reliability, flexible deployment (on-premise or cloud), and comprehensive integration capabilities across voice, messaging, and collaboration features. The company’s goal is to provide unified, scalable communications platforms that can be rapidly implemented to support evolving telecommunications needs in the B2B and residential markets.

Company Size

11-50

Company Stage

Early VC

Total Funding

$3.4M

Headquarters

Vienna, Austria

Founded

2008

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Simplify's Take

What believers are saying

  • Sipwise released mr14.1.1 on February 25 2026 and mr26.0.1 on May 1 2026.
  • The August 2026 calendar shows mr26.0 LTS support until May 2029.
  • Sipwise’s August 2026 Sip:phone push targets operators launching branded mobile voice services.

What critics are saying

  • CVE-2025-53399 exposed rtpengine media interception before 13.4.1.1, hurting trust.
  • The May 1 2026 mr26.0.1 LTS cadence still ships planned upgrades every few months.
  • ALE’s 2018 majority ownership makes Sipwise a subsidiary, limiting strategic independence.

What makes Sipwise unique

  • Sipwise owns NGCP plus rtpengine; that stack spans signaling, media, and apps.
  • The January 26 2026 release-cycle shift aligned mr26 LTS with three-year support.
  • Sip:phone stays white-label and integrated with NGCP provisioning, billing, and branding.

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Benefits

  • Hybrid Work Options
  • Remote Work Options
  • Flexible Work Hours

Growth & Insights and Company News

6 month growth

-16%

1 year growth

-16%

2 year growth

-16%
Sipwise
Jul 24th, 2026
The Sip:phone - A scalable mobile client for your NGCP platform.

The Sip:phone - A scalable mobile client for your NGCP platform. Sip:phone is not an isolated consumer softphone - it is a completely white-label mobile extension of the Sipwise NGCP platform, designed for operators who want to deliver a seamless voice experience tightly integrated with their SIP/NGCP services. Built on top of the Sipwise Next Generation Communication Platform (NGCP), Sip:phone aligns with the same architecture principles: modularity, operator control, predictable integration with billing and provisioning systems, and full branding flexibility so that it can be offered under your own identity to end customers. Strategic collaboration: Sipwise & DualBit. To accelerate both feature quality and UX polish, Sipwise GmbH work in active development with DualBit, a specialized software partner from Italy experienced in mobile client development for VoIP. This partnership ensures: * Modern, user-centric mobile interfaces * Feature alignment with backend service logic * Faster iterations based on operator feedback * Cross-platform compatibility (iOS & Android) Together, Sipwise GmbH bring a solution that is truly operator-grade, beyond simple off-the-shelf SIP clients. Key platform notes. Just as the Sipwise NGCP is a complete platform and not just a VoIP server, Sip:phone is an extension of that platform - designed to be: * Integrated into your OSS/BSS workflows * Managed with the same provisioning and billing APIs as the rest of NGCP * Operated under the same administrative framework that operators already trust Reach out its Sip:phone product page to have additional information about the app features. Early-Bird launch bundle. For new service launches, Sipwise is offering free branding and store set-up! This offer is only valid through a purchase of the Sip:phone, and for 2026 only. Its Sales team at Sipwise is available to guide you through the complete offering, help assess the right licensing model for your needs, discuss optional modules such as branding, support, or virtualization, and provide pricing and deployment guidance. You can contact them directly via [email protected], or request a personalized consultation to explore how SIP:phone can fit into your existing NGCP environment. For operators interested in exploring Sip:phone before committing, Sipwise GmbH provide a demo version of the APP that allows you to test its full capabilities in a safe, non-production environment. Ready to elevate your mobile voice services? Contact Sipwise Sales today and start transforming your NGCP CE deployment into a fully branded, operator-grade mobile experience with Sip:phone.