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Core Issue

This issue occurs when a user tries to log in to a phone configured for Cisco CallManager Extension Mobility and enters the user ID and Personal Identification Number (PIN).


The Error 0 error message requires that you ensure the neccessary Cisco CallManager Extension Mobility services are running. To resolve this issue, verify that all Cisco CallManager services are  running. If not, start the services. Refer to Control Center for information on viewing the status and to start and stop Cisco CallManager services for a particular server in a cluster.

For information on how to activate or deactivate services from the service activation web pages, refer to Service Activation .

For other related information, refer to these documents:


Problem Type

IP phones and other clients  (Client registration, faulty IP phone, etc.)

Call control software  (CallManager, CallManager Express, ICS7750, SRST, SS7 call agents)

Call Control


CallManager Features

Extension mobility and services

IP Phones and Clients

IP phone error messages

Failure Type

Error message

Cannot login or logout

When Problem Occurs

During login or logout

After entering username and password

End Where Problem is Heard or Device Type Involved

IP phone

IP Phone Errors

Error 0

CallManager Versions

CallManager 3.3

CallManager 4.x

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