... of the PSTN and what's in store for the future, it is important that you understand PSTN history and it's basics. As such, this chapter discusses the beginnings of the PSTN and explains ... OC-12, and OC-48 rates, which are 155.52 Mbps, 622.08 Mbps, and 2.488 Gbps, respectively. Network-to-network signaling types include in-band signaling methods such as Multi-Frequency (MF) and Robbed ... the digits and sends an Initial Address Message (IAM, or setup message) to the SS7 network. 5. The SS7 network reads the incoming IAM and sends a new IAM to Grandma's switch. 6. Grandma's...