Important Note: If you want to use USR (US Robotics) modem with P324 as dial backup, please use firmware upgrade utility to upgrade firmware to 3.61(JA.4)C0, else you can upgrade firmware via any approach including firmware upgrade utility. This utility only support changing firmware to V3.61(JA.4)C0. User can't use this utility to upgrade firmware to others version. (See Appendix 8 of release notes regarding Firmware Upgrade Utility)