Panasonic KX-TD500 Features Manual page 289

The display PT flashes the indication of the held party for five seconds at 15-second
intervals synchronizing with the tone.
Programming Guide References
• 2.3 Numbering Plan
– Call Waiting Set / Cancel
• 2.5 System Timer
– Hold Recall Time
Features Guide References
1.10 Holding Features
• Call Hold
User Manual References
Not applicable.
Features Guide
General Features
289