There are no practical limitations. The .wav file will be looped when it reaches the end, and will playback as long as a user is on the bridge. When the conference ends the file will start at the beginning again on the next call. Although there are not any length or size limitations it needs to be in this format: Mono, 8KHz, 16 bit PCM encoded. After replacing the file the SIP Service Manager will need to be restarted so UC will load the new file.
NOTE: The wav file is loaded into memory, so if it is too big there may be a RAM usage impact.
Message was edited by: matt - added note about RAM usage