ZyXEL Communications OMNI 56K Plus Series User Manual page 62

Omni 56K Plus Series User's Guide
Be sure you have the new firmware file on hand, then enter Y. The terminal will response as shown
6.
next. Remember that you must decompress compressed (.zip) files before you can upload them.
Click Transfer, then Send File to display the Send File screen.
7.
5-8 Firmware Upgrade