This looks to be a Yealink bug.
The OP has posted a workaround. This would make sense why Daniel didn’t have the issue after he moved to the cloud. The VOIP provider is probably blocking or rewriting the 503 packets.
This looks to be a Yealink bug.
The OP has posted a workaround. This would make sense why Daniel didn’t have the issue after he moved to the cloud. The VOIP provider is probably blocking or rewriting the 503 packets.