Please find ASP code below for retrieving an MMS message and storing it on the local drive:
<%
Username = "MyUsername"
Password = "MyPassword"
From = Request("from")
MMSSubject= Request("text")
MessageId = Request("msgid")
FileList = Request("filelist")
'NOTES:
'You must create a folder called C:\MMSFiles
'You must also make sure that PHP scripts have permission to write to this folder
GetMMSFiles Username, Password, MessageId, FileList, "C:\MMSFiles\"
Function GetMMSFiles ( Username, Password, MessageId, FileList, DestinationPath )
    Set objHTTP = Server.CreateObject("MSXML2.ServerXMLHTTP")
    FileListArray = Split(FileList,",")
    For Each MMSFilename in FileListArray 
        GetMMSFile objHTTP, Username, Password, MessageId, MMSFilename, DestinationPath & MMSFilename
    Next
    Set objHTTP = nothing
End Function
Function GetMMSFile ( objHTTP, Username, Password, MessageId, MMSFile, DestinationFilename )
    Url = "http://www.intellisoftware.co.uk/smsgateway/retrievemms.aspx" & _ 
		"?username=" & Server.UrlEncode(Username) & _
		"&password=" & Server.UrlEncode(Password) & _
		"&msgid=" & Server.UrlEncode(MessageId) & _
		"&msgpart=" & Server.UrlEncode(MMSFile)
    objHTTP.Open "GET", Url, False
    objHTTP.Send
    If objHTTP.Status = 200 Then
	Const adTypeBinary = 1
	Const adSaveCreateOverWrite = 2
	set objStream = createobject("ADODB.Stream")
	objStream.Type = adTypeBinary
	objStream.Open
	objStream.Write objHTTP.ResponseBody
	objStream.SaveToFile DestinationFilename, adSaveCreateOverWrite
	objStream.Close
	set objStream = nothing
	'Check for error from the IntelliSoftware platform
	ContentType = objHTTP.getResponseHeader("content-type")
	If Left(ContentType,5) = "text/" Then
	    If Left(objHTTP.ResponseText,4) = "ERR:" Then
		If Len(objHTTP.ResponseText) < 100 Then
			Response.Write objHTTP.ResponseText & " (" & "MMSFilename:" & MMSFile & ")<BR>"
		End If
	    End If
	End If
    Else
	Response.Write "HTTP Fetch Error:" & objHTTP.Status & "<BR>"
    End If
End Function
%>