How many STS1s in an OC3?

An OC-3 (Optical Carrier Level 3) can carry 3 STS-1 (Synchronous Transport Signal level 1) signals. Since each STS-1 has a data rate of 51.84 Mbps, an OC-3 has a total data rate of 155.52 Mbps, which is achieved by multiplexing three STS-1 signals together.