For some reason when I add the hostname (as instructed by provider) for proxy server, they do not see any attemps from my end trying to register. If I substitute this with an IP address, they see registration attemps, however it fails due to them requiring a FQDN instead of an IP address.
Following up on Adam's post, do they require DNS SRV to be configured? You can use the ping tool under Status -> Support Tools to see if you can ping the proxy from the UC320W. Note: This won't help if your provider requires DNS SRV lookup.
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