Cisco 7900 series IP Phone users do not receive a dial tone from Cisco
CallManager, and the High Traffic Try Again
Later error messages appears on the phone display when they go
off-hook. This document discusses how to troubleshoot this issue.
There are no specific requirements for this document.
The information in this document is based on the Cisco CallManager
The information in this document was created from the devices in a
specific lab environment. All of the devices used in this document started with
a cleared (default) configuration. If your network is live, make sure that you
understand the potential impact of any command.
Technical Tips Conventions for more information on document
Cisco 7900 IP Phones do not receive a dial tone from Cisco CallManager
and instead receive a reorder/busy tone when the phone goes off-hook. The
High Traffic Try Again Later error message
appears on the LCD display of the IP Phone.
Note: This issue occurs intermittently.
The High Traffic Try Again Later error
message that appears on the IP Phones indicates this issue:
Whenever the LowPriorityQueueThrottlingFlag Cisco
CallManager service parameter is set to TRUE and the Low
Priority queue is over the limit specified by the
LowPriorityQueueThrottlingMaxCount Cisco CallManager service
parameter, the High Traffic Try Again Later
error message appears on the LCD display of any IP Phone that is registered to
this Cisco CallManager server and that attempts to go off-hook and make a new
call. By default, this message appears on the phone if the Low Priority queue
gets deeper than 20 signals.
Generally, the Cisco CallManager works fine as long as the Low
Priority queue does not get higher than 100. Therefore, if you never see the
Low Priority queue go higher than 75, you can configure the
LowPriorityQueueThrottlingMaxCount = 100 Cisco CallManager
service parameter in order to overcome this issue.
It is also recommended to check the CPU utilization and the disk space
usage. If they are high, you need to clear the hard disk space and
the CDR/CAR database.