These are your tasks:

At 1&1, the Development Access department is responsible for in-house
software development for the provision of high-quality voice and data
services via the access technologies DSL, DOCSIS (cable), fiber optics
and 5G mobile communications. As a central part of this, the VoIP team
is responsible for the software development and quality assurance of
the telephony service systems and, with around 5 million VoIP customers
and almost 14 million telephone numbers, represents the world’s largest
open source-supported telephony solution.

The international team is looking for VoIP Developers (m/f/d) who are
willing to take on responsibility, appreciate creative freedom in an
agile environment and are motivated to actively help shape the team’s
system landscape. In a supportive work environment, the core tasks
consist of:

• Developing new, innovative products in the VoIP environment in close
  collaboration with the peripheral teams.

• Responsibility for planning, analysis, design, development and
  testing of system modules and components, as well as enhancements to
  the 1&1 VoIP infrastructure.

• Integrating and extending projects from the open source community and
  working closely with other open source developers.

• Contributing own ideas and actively shaping the system landscape to
  continuously improve existing software components.

What we are looking for:

You have successfully completed your studies in computer science or
information technology and have the ability to design, implement and
document software systems based on technical specifications? Are you
open-minded towards Linux/Open Source and motivated to take your next
career step in one of Germany’s leading telecommunications companies?
Then we look forward to receiving your application and would like to
see the following profile:

• Sound knowledge in the IP telephony environment in the SIP/RTP and
  SDP protocols.

• Experience with open source projects in the field of VoIP such as
  Kamailio or RTPengine.

• Good knowledge of Linux and scripting languages (Bash and Python), as
  well as good knowledge of C/C++.

• Good knowledge of networking (TCP/IP, IPv6), network architecture,
  network-oriented server services and databases (SQL).

• Strong written and spoken English skills are required, as well as
  enjoyment of agile software development.

• Bonus qualifications such as experience from the environment of IMS
  and 5G Basic knowledge of configuration management tools such as
  Ansible or Puppet.

This position requires a permanent residence in Germany due to the social security law.