Current State:

There is no documented character limit for incoming call auto-attendant in the field Use text-to-speech, but there is a limit when exceeding 250 characters or more than 25 prompts.

1. Go to the JSM Operations incoming call
2. Incoming call configuration menu
3. Try to add a text longer than 250 characters.

Proposed Future State:

It should allow text longer than 250 characters, a limit of 1000 characters would be good.

Alternative (e.g. Third Party Plugin):

The workaround is to upload the file.