When using supported IP phones with the Branch Gateway, the IP phones require the downloading of the settings file and the upgrade scripts. These files are stored in the script banks in NVRAM and are preserved in the event of a reset or power failure. There are two script banks.

In addition, each phone can have a booter application and a phone application. There are four banks that can store up to two phone images (booter and phone application files) at any given time. Since the image files are stored in RAM, a reset or power failure erases these files. The image files are used only for upgrading the IP phone, so there is no need to store them permanently. However, the scripts are used by the IP phones when they are reset, and are therefore stored in NVRAM. You can upgrade up to two types of phones and then release the banks for use with another IP phone type.

There are cases where the image files are the same for different IP phone types. In these cases, you can download the image files once for the IP phones that use the same image. The scripts are global to all the supported IP phone images.

You can download and then upload setting script files in order to update their content. It is not recommended to change the upgrade script.

By default, the RAM allocation for TFTP server is 10 MB. You can increase the RAM allocation for TFTP server to up to 11.264 MB at the expense of the Sniffer cache application. The maximum RAM for both applications is 12 MB.

There are four image banks, supporting two IP phone images in RAM, provided the combined file sizes do not exceed the RAM allocation for TFTP server. The maximum size for a booter application or phone application file is 4.5 MB. Thus, it is possible that in some cases, the allocation may only suffice for one complete IP phone image and not two.