You can send logs to Splunk and configure any available port to listen to those syslog messages:
[tcp://<remote server>:<port>]
* Configures the input to listen on a specific TCP network port.
[udp://<remote server>:<port>]
* Configures the input to listen on a specific UDP network port.
https://docs.splunk.com/Documentation/Splunk/latest/Admin/Inputsconf
Usually sending syslog directly to Splunk is not a best practice but you could instead use an intermediate Syslog-NG or Rsyslog to write it to disk, and have a Splunk UF monitoring those files.
If your Polycom can send HTTP data, you can also enabel HEC on Splunk Indexers and listen to that stream of data directly into Splunk:
https://docs.splunk.com/Documentation/Splunk/7.3.0/Data/UsetheHTTPEventCollector
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