The three vertical ionosondes operated by the Swedish Institute of Space Physics have been modernized and integrated with a data network. They are collectively called SIN, the Swedish Ionosonde Network. The authors describe a graphical user interface for running and displaying results from the ionosondes. The authors also show examples of measurements performed with the ionosondes. The measurements have several uses such as: regular ionospheric sounding giving long term statistics of the ionosphere; complementing radar and satellite measurements for understanding the physics of the near Earth environment, and a channel probe for radio users on the HF band. The authors discuss the use of the ionosondes as data collection instruments for the development of models of the ionospheric transfer function. An example of a method used to monitor ionospheric vertical motion is also shown.