Haim, HR> SMPP is a good example to what I am looking for, and I am trying to see if HR> other HR> protocol foreseen in the future (or past) have the same characteristics: RFC1692, Transport Multiplexing Protocol, was designed for the operation you appear to be describing. As long as you have access to the necessary bits of protocol software in the stack, it's a simple, flexible and efficient mechanism. d/ -- Dave Crocker <dcrocker-at-brandenburg-dot-com> Brandenburg InternetWorking <www.brandenburg.com> Sunnyvale, CA USA <tel:+1.408.246.8253>