string filePath = “file://” + path + txtTitle.Text;
var mmsIntent = new Intent(Android.Content.Intent.ActionSend);
mmsIntent.PutExtra(Android.Content.Intent.ExtraSubject, “audio is in the attachment”);

mmsIntent.PutExtra(“sms_body”,”Please see audio attachment”);

mmsIntent.PutExtra(Android.Content.Intent.ExtraStream, Android.Net.Uri.Parse(filePath));

System.IO.FileInfo fileToBeSentAsAttachment = new System.IO.FileInfo(path + txtTitle.Text);
if (fileToBeSentAsAttachment.Exists)
{
mmsIntent.PutExtra(Intent.ExtraStream, Android.Net.Uri.Parse(filePath));
mmsIntent.SetType(“audio/*”);
}

StartActivity(Intent.CreateChooser(mmsIntent, “Send”));