ABSTRACT CubeCat-1 is an educational oriented Cubesat - a standard, small form factor satellite project started in 2008 in the UPC in Barcelona, under the supervision of professors Adriano Camps and Juan Ramos, with many students involved. The main objective of the CubeCat-1 project is to get students involved in a hands-on multidisciplinary group frame work. A primary mission requirement of any satellite is the ability to exchange information with a ground based command station, establishing a reliable link to send telemetry, health status from sensors and scientific payload data and being able to receive commands from Earth. The goal of this project is to present the design and software implementation of part of the communications subsystem for the Cubesat, continuing the work started by the first CubeCat-1 team (at that time named UPCSat-1) and referenced in the master thesis. It is presented: · The description of the hardware. · The design and implementation of the software responsible for encoding and decoding telemetry and payload data. · The Ground segment description and tests performed to guarantee the correct communication with the Cubesat and the integration with the GENSO network. · Lessons learned, solutions and remaining issues are presented in detail.