User guide

August 2001 225

Immediate Start

Table 36 shows the pattern of bits transmitted by the CO and

CPE in the Immediate Start protocol.

Table 36. Immediate Start: CO Calls CPE

In the Immediate Start protocol, both ends transmit 00 in the

idle state. When the CO seizes the line, it transmits 11, and

continues to transmit that pattern throughout the conversation.

The CO waits a certain amount of time after seizing the line

then sends digits, without confirming that the receiving end is

ready. After the CO sends digits, the CPE answers the call by

transmitting 11. To disconnect, both ends transmit 00.

The CO usually starts sending digits within 200 ms of the line

seizure, so the application must be ready to receive digits almost

immediately after receiving the seizure. When the application

initiates a call, it sends digits 200 ms after seizing the line.

When the CPE disconnects, RHT_DISCONNECT or

RHT_ON_HOOK waits for the CO to disconnect to a maximum

time specified by RDG_REMOTE_IDLE_TIMEOUT.

If the network you are connected to accepts call transfers, the

HookFlash duration is determined by

RDG_LOCAL_FLASH_DUR.

Status CO CPE Timing Parameter

Idle 00 00

Seizure 11 --> 00

CO sends digits 11 00

Answer 11 <-- 11

Conversation 11 11

CPE disconnects 11 <-- 00

CO disconnects 00 --> 00 RDG_REMOTE_IDLE_TIMEOUT

HookFlash 11 <-- 11/00/11 RDG_LOCAL_FLASH_DUR

11/00/11 --> 11