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What an OC-48 contains

An OC-48 carries 32,256 DS0s, per Telcordia GR-253 and ANSI T1.107.

OC-48 → 48 × OC-1 (STS-1) → 28 × DS1 → 24 × DS0

48 OC-1s
48 × 28 = 1,344 DS1s
48 × 28 × 24 = 32,256 DS0s

E1 mapping: 1,008 E1s, which is 30,240 voice channels at 30 per E1. E1s in an OC-48.

Down to DS0

48 × OC-1 (STS-1) Telcordia GR-25348 × OC-1 (STS-1). Channelized OC-48 is 48 STS-1s.
1. 28 × DS1 Telcordia GR-253Seven VT groups × four VT1.5 (DS1).
  1. 24 × DS0 ANSI T1.10724 payload timeslots. The framing bit adds 8 kbit/s and brings the line rate to 1.544 Mbit/s.
2. 1 × DS3 Telcordia GR-253Asynchronous DS3 mapping into the STS-1 synchronous payload envelope.
3. 7 × DS2 Telcordia GR-253Seven VT groups, one VT6 (DS2) each.
4. 21 × E1 Telcordia GR-253Seven VT groups × three VT2 (E1).
4 × OC-12 Telcordia GR-2534 × OC-12. Channelized OC-48 is 48 STS-1s.
16 × OC-3 Telcordia GR-25316 × OC-3. Channelized OC-48 is 48 STS-1s.

OC-48 rates and aliases