Xamarin vs using twilio client

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C#

Android

Xamarin

i want to use sip registration with String text Number Password server and Port
i am using twilio twilio using web registration i don't need it

  public async void OnInitialized ()
    {
        Console.WriteLine ("Twilio SDK is ready.");

        try {
            var client = new HttpClient ();
            var token = await client.GetStringAsync(");

            Device = Twilio.CreateDevice(token, null);

            var intent  = new Intent(context, typeof(MainActivity));
            var pendingIntent = PendingIntent.GetActivity(context, 0, intent, PendingIntentFlags.UpdateCurrent);

            Device.SetIncomingIntent(pendingIntent);

            Device.SetDeviceListener(this);

        } catch (Exception ex) {
            Console.WriteLine ("Error: " + ex.Message);
        }
    }
here is folowing code how it is registering but i wan tto register likee I ahve Pone number Number : 255 Password:15gfg2 ServerLoc:192.168.0.5 SIPPOrts:5060 
anyone help plz

What I have tried:

var client = new HttpClient ();
var token = await client.GetStringAsync("i treid here to take some stringed infos but not working again :/");