Cisco Systems 2600 appendix VC-821

Command

Purpose

Step 4

Router(config-voiceport)# caller-id alerting

(FXO ports, only when caller-ID alerting

dsp-pre-alloc

line-reversal is required) Configure this command

on the FXO port when the incoming subscriber

telephone line uses line polarity reversal to signal

the start of caller-ID information transmission.

The Cisco FXO interface cannot detect

line-reversal alerting in the on-hook state. For this

reason, DSPs must be pre-allocated to serve the

Type 1 caller ID information when it arrives.

Preallocating the DSPs enables the DSP to

continuously monitor for the arrival of caller-ID

information.

Step 5

Router(config-voiceport)#caller-id alerting pre-ring

(FXS ports only) Configure this setting only when

the attached telephone device requires the pre-ring

(immediate ring) method to signal the start of a

caller ID information. The command activates a

250-ms pre-ring.