In general, when performing updates using the Custom File format, we can typically get away with the MAC ADDRESS or DEVICE NAME field. The file might look something like:
MACADDRESSSEP001BD4546BB0SEP00215554F98F
To upload the custom update file to Unified Communications Manager, navigate to Bulk Administration | Upload/Download Files.
Click on Add New to upload a new file.
Specify the File we previously created.
From the Select The Target drop-down, select Phones.
From the Select Transaction Type drop-down, select Update Phones – Custom File:
Click on Save.
Navigate to the Update Phone | Custom File page under Bulk Administration | Phones.
From the Custom File drop-down, select the file we just uploaded and click on Find.
Click on Next.
Under the section Logout/Reset/Restart, select Apply Config.
Under the Device Information section, check the boxes next to:
Media Resource Group List
User Hold MOH Audio Source
Network Hold MOH Audio Source
Select...