CRBT(Color Ring Back Tone) is a Telecommunication VAS in which the caller can hear songs tune if the called party has CRBT enabled. This article explains how CRBT operates within the Intelligent Network architecture. The MSC (or SSP) must support the CAMEL Application Part(CAP) Phase 4 (or INAP CS2). The MSCs, SCPs and IPs are all interconnected as shown in the figure. The IPs(Intelligent Peripherals) are responsible for playing the CRBT tunes as directed by the SCP. The IN has separate SCPs dedicated for CRBT. The number of SCP depends on the number of mobile subscriber the Network Operator ....