When being powered up, the control unit looks for a valid ip500v2.bin binary file to load. It does this using the sources below in the order shown, skipping to the next source if the file is not present or is not valid.
1.System SD card /primary folder.
2.The control unit's own internal non-volatile memory. Once a system has been installed, it uses its non-volatile memory to keep copies of the configuration and system binary files it is using. These can be used to restore operation during a system reboot. Note that though a system can boot from non-volatile memory, a System SD card must still be present for correct system operation.
3.System SD card /backup folder.
4.Optional SD card /primary folder.
5.Optional SD card /backup folder.
6.If no file is found, the control unit falls back to making BOOTP requests to the network. IP Office Manager can respond the BOOTP request. See Erasing the Operational Firmware.
Once a valid ip500v2.bin file is found, the IP Office control unit will load that firmware. The source from which the control unit binary file was loaded is then used to load further files.
Configuration File Loading
Having installed the necessary system firmware files as above, the IP500 V2A control unit requires a configuration file:
•If the IP500 V2A booted using binary files from an SD card location, it looks for a valid configuration file in the same location.
•If a configuration file is present and valid, it is loaded.
•If a configuration file is present but is not valid, load the configuration copy in its non-volatile memory if present, else it assumes a default configuration.
•If a configuration file is not present, use the non-volatile memory copy as above unless the reboot is as a result of a default system command.
•If the IP500 V2A booted using binary files from its non-volatile memory, it will also load the configuration copy from that location.
•It will indicate a boot alarm (see below).
•It will attempt to restore the firmware file in the System SD card's /primary folder using the copy in its non-volatile memory.
•The normal boot up process of upgrading expansion module firmware does not occur. If the File | Advanced | Upgrade command is used, only external expansion modules actually present in the system are listed for upgrade.
Post Boot Operation
During normal operation, configuration and binary files sent to the System SD card /primary folder using IP Office Manager are also written to the non-volatile memory.
If the system has booted from its non-volatile memory due to an SD card problem, it is still possible to upgrade the ip500v2.bin file using the IP Office upgrade wizard.
Boot Alarms
The following apply if the IP500 V2A boots using software other than that in its System SD /primary folder:
•An alarm will be shown in the System Status Application. It will also generate an alarm if the card in any slot is not compatible. These alarms are also output as SNMP, Syslog or email alarms.
•The IP Office Manager Select IP Office menu will display an 
icon, indicating that the IP Office system is running using software other than from the System SD card's primary folder.
•The configuration can be read but will be read only. Attempting to send a configuration to the system will cause the error message Failed to save configuration data. (Internal error).
Bypassing the System SD Card Primary Folder
The control unit can be forced to bypass the System SD card's /primary folder and non-volatile memory when starting. This is done by pressing the Aux button while applying power to the control unit.
This action may be necessary if, following an upgrade of the IP Office system, it is determined that a roll back to the previously backed up firmware and configuration is required. Using the Aux button should restore system operation using the /backup folder files while the installer then restores the contents of the /primary folder to a previous release.