public override bool SendMessageMMS(string phoneNumber, string text, AttachmentData attachment)
 {
     return SendMessageSMS (phoneNumber, text);
     // MMS not supported yet
 }
 public abstract bool SendMessageMMS(string phoneNumber, string text, AttachmentData attachment);
 public override bool SendMessageMMS(string phoneNumber, string text, AttachmentData attachment)
 {
     throw new NotImplementedException();
 }
        public override async Task<bool> SendMessageMMS(string phoneNumber, string text, AttachmentData attachment)
        {

            //Cant send MMS programatically
            throw new NotImplementedException();
        }
 public abstract Task <bool> SendMessageMMS(string phoneNumber, string text, AttachmentData attachment);