Overview
When attempting to call toll-free numbers, users may encounter a 503 Service Unavailable error due to an 'Invalid Line' in the SDP message. This issue can arise if IPv6 is enabled on the network, causing the switch to not recognize the SDP information. The solution involves configuring the network to prefer IPv4.
Information
To resolve the issue of receiving a 503 Service Unavailable error when calling toll-free numbers due to an 'Invalid Line' in the SDP message, follow these steps:
- Access the network configuration settings.
- Locate the parameter for IP address mode.
- Set the parameter
static.network.ip_address_modeto0to prefer IPv4 over IPv6. - Save the changes and restart the network services if necessary.
This configuration change should resolve the issue by ensuring the network uses IPv4, which is compatible with the SDP message requirements.
Frequently Asked Questions
- What causes the 503 Service Unavailable error when calling toll-free numbers?
- The error can be caused by an 'Invalid Line' in the SDP message due to IPv6 being enabled on the network, which the switch does not recognize.
- How can I resolve the 'Invalid Line' issue in the SDP message?
- You can resolve this issue by configuring the network to prefer IPv4. Set the parameter
static.network.ip_address_modeto0in the network settings. - Do I need to restart the network services after changing the IP address mode?
- Yes, it is recommended to restart the network services to ensure the changes take effect and resolve the issue.
Priyanka Bhotika
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