Cisco 12 Series IP Phones

Field Notice: Cisco IP Phone and Cisco IOS DHCP Server

July 28, 1999

Products Affected



Cisco 12 SP+ and 30 VIP IP Phones

A Cisco IP phone cannot be a DHCP client for a Cisco router running Cisco IOS 12.0

Problem Description

Cisco IP telephones will incorrectly reject DHCP offers that do not have an "End of Options" option set on the server.

Cisco DHCP Server running Cisco IOS 12.0 does not send an "End Of Options" option with all offers.

Incorrectly programmed DHCP clients (such as older Cisco IP telephones) may incorrectly ignore such offers and not be able to obtain an IP address from the Cisco IOS DHCP server.

Problem Symptoms

The Cisco IP telephones will fail in obtaining an IP address from the Cisco IOS 12.0 DHCP server and will not boot up.


The problem occurs only between Cisco (Selsius) phones and Cisco IOS DHCP server. A Selsius phone cannot be a DHCP client for a Cisco router running Cisco IOS 12.0. The are two bug IDs associated with the problem, CSCdm57932 (IP phone) and CSCdm57935 (Cisco IOS DHCP server) and they cross reference each other.

If you are a registered CCO user and you have logged in, you can view the bug details.

View bug details for CSCdm57932 (registered customers only)

View bug details for CSCdm57935 (registered customers only)


Workaround 1

Disable DHCP at the phone and program a fixed IP address.

Workaround 2

Use an alternate DHCP server, such as Cisco Network Registrar (CNR).

Workaround 3

Use a Bootp server. Bootp.exe is included with the CM software.


The load that this will be fixed in is P00xL202. This will be available after it has been thoroughly tested and will be included in the next Call Manager 2.3 maintenance release, scheduled for 08/1999.

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:

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