What is ISUP (Integrated Services Digital Network User Part)?

The Integrated Services Digital Network User Part is essential of Signaling System No. 7 (SS7), which is utilized to establish phone calls in the public switched phone organization. ISUP is likewise utilized to exchange status data for, and allow management of, the accessible circuits. At the point when ISUP upholds a call to be set up effectively, a switch will signal call-related data to the next switch in the network utilizing ISUP messages.