HIP (Host Interface Protocol) is a multiplexing layer designed to allow several types of message streams to share the same physical link layer — CnS is one of the supported streams.

HIP is used to carry control and status data between the modem and the host to provide management of the modem device. This management consists of:

• Non‐volatile configuration of the device

• Run‐　　ime configuration of the device

• Status reporting and monitoring of the device

This protocol does not include checksums. It relies on a high‐
eliability physical interface between the host and the modem to reduce the processing burden on the microprocessor.