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This topic describes how to troubleshoot a fault that occurs when an IMS user is called through the SIP trunk.
Symptom
When calling the IMS user, the intra-office user hears the busy tone.
Possible Causes
The possible causes are as follows:
ϒ⁄The registration group configuration is incorrect.
ϒ⁄The calling number format does not meet IMS (86+area code+number) requirements.
ϒ⁄The registration group ID is not set.
Parent Topic: SIP Trunk Fault