Cannot obtain token using SOAP service

I cannot obtain token using SOAP service. This is the request I am doing based on the WSDL example in SOAP-UI:

<soapenv:Envelope xmlns:soapenv=http://schemas.xmlsoap.org/soap/envelope/xmlns:xpr=http://videoos.net/2/XProtectCSServerCommand>

soapenv:Header/

soapenv:Body

 <xpr:Login>

    <!--Optional:-->

    <xpr:instanceId>80065a47-681e-4c0e-bcdf-e304f9d372b8</xpr:instanceId>

 </xpr:Login>

</soapenv:Body>

</soapenv:Envelope>

I always receive an error that says: Missing mandatory field “parameters”. I thought I should provide also username, password or other parameters, but I couldn’t figure it out how should be passed.

Can somebody provide an example if a complete request? Thank you!

TCP video viewer sample might be helpful for you to explore -

https://doc.developer.milestonesys.com/html/index.html?base=samples/protocolsamples/tcpvideoviewer/readme.html&tree=tree_3.html