. The phonebook functionality is typically accessed via specific AT commands (e.g., AT+CPBR for reading phonebook entries) rather than manually installing an .ipa file.
Software suites like the Gigaset Configuration Tool or Service Tool for GM30 . download-gm30e-telefonbuch-ipa
If you are working with this module, you will likely need the documentation for the download-gm30e-telefonbuch-ipa