The WebDialer service is already present on CUCM, it just needs to be activated.

Applications can interact with WebDialer via javascript or SOAP, please see the Getting Started and Documentation areas of the WebDialer developer site for more details:

http://developer.cisco.com/web/webdialer/home

I was able to use the Javascript function to get the Webdialer popup window. I am trying to make a call from C# code (by using the code in another thread in this forum) but it does not make any call. It says: "Missing parameters in the request" CallResponse object.

Is there a C# sample also somewhere?

This is the code I am using:

protected void Button1_Click(object sender, EventArgs e)
{
System.Net.ServicePointManager.CertificatePolicy = new TrustAllCertificatePolicy();
WebdialerSoap wb = new WebdialerSoap();

Credential cred = new Credential();
cred.userID = "userId";
cred.password = "password";

UserProfile upr = new UserProfile();
upr.deviceName = "SEP000......";
upr.lineNumber = "1";

CallResponse callRes = new CallResponse();

callRes = wb.makeCallSoap(cred, "7073", upr);
}

Thanks so much.

Got it. I was missing the user for the profile.

upr.user = cred.userID;

WebDialer uses UCM's CTI interface to effect the outdial, taking control of the calling device and initiating a call request.
 
In your situation, it _may_ be possible in that:
 
- CTI does support control of analog devices on VG248 gateways (not VG224s, though)
- The analog device/port must be associated to your UCM user account in the standard fashion
- The analog device must already be off-hook when the WebDialer request is made
 
If, as I suspect, you just want 2 numbers connected, regardless of where/what they may be (for example they could be across a trunk,) then WebDialer is probably not going to suffice.  You could implement something like that fairly easily via the CUAE, having it outdial each of the two phones, and then connecting them together.

The CUAE Tech Center is here: http://developer.cisco.com/web/cuae/home.  There is quite a bit of documentation and several samples available to get you started.  Note this product requires a separate CUAE server to run the app on, though you can download the software and get started on a commodity PC for free.
 
If that's too much complexity, you can also accomplish what you want here via TAPI (Windows) or JTAPI (Java) call control APIs.