The customer is using a Cisco 2911 Voice Gateway configured with CME and connected via a SIP trunk from the ISP.
There have been no recent configuration changes on the voice gateway; however, the customer is currently experiencing issues with outgoing mobile calls as described below:
Firmware: c2900-universalk9-mz.SPA.157-3.M8.bin
Service Type: SIP Trunk
Issue Details:
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Outgoing calls to Mobile Service Provider 1: Fail consistently — calls drop immediately after dialing.
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Outgoing calls to Mobile Service Provider 2: Work most of the time, but occasionally drop before ringing.
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Incoming calls: Working fine.
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SIP Trunk: Provided by Mobile Service Provider 1.
A technician from Mobile Service Provider 1 tested outgoing calls using their softphone and confirmed that calls work correctly from their side. They concluded that the issue lies within the Cisco Voice Gateway.
However, it appears that this issue may be caused by parameter or signaling changes on the service provider’s side, which have not been disclosed. When tested through the provider’s ONT device or softphone, calls work normally, indicating a potential SIP interoperability or header mismatch issue.
Similar behavior has been observed at other customer sites using Cisco Voice Gateways, which further supports the possibility of a provider-side SIP parameter change.
