SIMOCOM U is built on Visual Basic 6. Download from Microsoft (free) and install it first.
Siemens has transitioned Simocom U to "Lifecycle Status: Discontinued." It is no longer actively marketed, but the files are preserved in the Siemens Support Center archives. Siemens Simocom U Software Download
Access the SimoCom U V14.03.02 package for the most current stable release. SIMOCOM U is built on Visual Basic 6