this is a variation of a script posted at https://gallery.technet.microsoft.com/SONOS-PowerShell-500c9878 that uses Invoke-Webrequest.

Dev-PSSonos.ps1

<#
this is a variation of a script posted at
https://gallery.technet.microsoft.com/SONOS-PowerShell-500c9878

that uses Invoke-Webrequest.

This is very much a work in progress

other resources
http://musicpartners.sonos.com/?q=node/224#toc4
http://musicpartners.sonos.com/node/134
http://www.programmableweb.com/api/sonos-music/source-code
http://stackoverflow.com/questions/tagged/sonos
#>

[cmdletbinding()]
Param(

[Parameter(Mandatory)]
[ValidateSet("Play","Pause","Info")]
[String]$Action,
[ValidateNotNullorEmpty()]
[string]$ip = "172.16.10.179",
[ValidateNotNullorEmpty()]
[int]$port = 1400 
)


#Info doesn't work yet because I have to get and parse the response
Switch ($Action) {
"Pause" { $soapAction = @{
        "path" = "/MediaRenderer/AVTransport/Control"
        "soapAction" = "urn:schemas-upnp-org:service:AVTransport:1#Pause"
        "message" =  '<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"><s:Body><u:Pause xmlns:u="urn:schemas-upnp-org:service:AVTransport:1"><InstanceID>0</InstanceID></u:Pause></s:Body></s:Envelope>'
        }
        }

"Play" { $soapAction =  @{
    path = "/MediaRenderer/AVTransport/Control"
    soapAction = "urn:schemas-upnp-org:service:AVTransport:1#Play"
    message = '<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"><s:Body><u:Play xmlns:u="urn:schemas-upnp-org:service:AVTransport:1"><InstanceID>0</InstanceID><Speed>1</Speed></u:Play></s:Body></s:Envelope>'
    }
    }
"Info" {
 $soapAction =  @{
    path = "/MediaRenderer/AVTransport/Control"
    soapAction = "urn:schemas-upnp-org:service:AVTransport:1#GetPositionInfo"
    message = '<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"><s:Body><u:GetPositionInfo xmlns:u="urn:schemas-upnp-org:service:AVTransport:1"><InstanceID>0</InstanceID></u:GetPositionInfo></s:Body></s:Envelope>'
    }

}
}


$uri = "http://$($ip):$port$($soapaction.path)"

Write-Verbose "Connecting to $uri"

Write-Verbose "Action = $($soapAction.soapAction)"

# Set Headers
$headers = @{
'Accept-Encoding' = 'gzip'
SOAPACTION = $soapAction.soapAction
}

Write-Verbose "Headers"
Write-Verbose ($headers | out-string)

[xml]$body = $soapAction.message
Write-Verbose "Body = $($soapaction.message)"


$paramHash = @{
 Uri = $uri
 Headers = $headers
 ContentType = 'text/xml; charset="UTF-8"'
 DisableKeepAlive = $True
 Method = 'Post'
 Body = $body
 UseBasicParsing = $True
 ErrorAction = "Stop"
}

Write-Verbose "Using param hash"
Write-Verbose ($paramHash | out-string)

Try {
  Invoke-WebRequest @paramHash 
}

Catch {
  $_ | select *
<#
if ($_.Exception.gettype().name -ne 'xArgumentNullException') {
  $_
 }
 #>

}

I have hardcoded the IP address of one of my Sonos units. You'll of course need to change that.