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Document ID: 48262
Contents
Introduction
Prerequisites
Requirements
Components Used
Conventions
Recommended T1 Signals
E&M
Wink Start
ESF
DTMF
Ground Start
Signals Not Recommended
SF
AMI
Loop Start
T1 PIN Requirements
Related Information
Introduction
This document explains T1 requirements and terminology for Cisco MeetingPlace servers.
Prerequisites
Requirements
There are no specific requirements for this document.
Components Used
The information in this document is based on Cisco MeetingPlace server software (all versions).
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
Conventions
For more information on document conventions, refer to the Cisco Technical Tips Conventions.
Recommended T1 Signals
It is recommended that the T1s be configured with these signals:
E&M
Ear and Mouth (E&M) is equivalent to receive and transmit.
Wink Start
Wink Start provides positive answer/end disconnect supervision. For example, if a hang-up signal is given from Cisco MeetingPlace, the PBX or central office (CO) follows and hangs up (releases the port). The same happens if Cisco MeetingPlace answers—the PBX or CO answers. Basically, an answer signal causes an answer, a hang-up signal causes a hang-up. Wink primarily swaps the voltage potential between the tip and ring. *
Note: * A tip is one side of the line. Loop Start and Ground Start have only one pair of wires (one is tip and one is ring). T1 has two pairs. One pair is used to transmit and one pair is used to receive. The transmit pair has a tip and a ring and the receive pair has a tip and a ring. Tip and ring have different voltage potentials.
ESF
Extended Super Frame (ESF) takes 24 separate frames/circuits/ports for each T1.
DTMF
Dual Tone Multiple Frequency (DTMF) is required. This signal executes the Cisco MeetingPlace prompts, similar to a Return or Enter key on a keyboard.
Ground Start
Ground Start acts and is programmed just like the Loop Start trunks. This signal is used primarily on analog phones. It is the opposite of Wink Start. This type of signal is necessary because of the need to accommodate the CO trunks that are simulating analog, but the Ground Start signal provides positive disconnect supervisions. Ground Start provides better supervisions than Loop Start because Loop works by current flow, and if the line gets shorted, there is still current flow. Ground Start sends a disconnect signal by addition or subtraction of voltage. *
Note: This signal is only needed when the telephone company (telco) is simulating two-way business trunk. This is to ensure that the customer's trunks do not get hung.
Signals Not Recommended
It is recommended that the T1s not be configured with these signals:
SF
Super Frame (SF), also known as D4, is not recommended. It takes 12 separate frames/circuits/ports per T1.
AMI
Alternate Mark Inversion (AMI), also known as Jam Bit, is not recommended. The T1 source (from the distant end, not from the Cisco MeetingPlace server) gives false yellow alarms on the Cisco MeetingPlace Server. If these false yellow alarms occur frequently, this could bring the T1s down. The CO shuts off its equipment if a tolerant level is reached.
Loop Start
The Loop Start signal, also known as Line Side T1, is not recommended. This signal is primarily used on analog phones. It is the opposite of Wink Start. Hung ports are common.
T1 PIN Requirements
PINS 1, 2, 4, and 5 are required for the T1 connector hardware. What these PINS do is described below.
CO/PBX MUST USE PINS MeetingPlace Tip Transmit 1 Record Tip Ring Transmit 2 Record Ring Tip Record 4 Transmit Tip Ring Record 5 Transmit Rin
Related Information
- Voice Technology Support
- Voice and Unified Communications Product Support
- Recommended Reading: Troubleshooting Cisco IP Telephony
- Technical Support - Cisco Systems
| Updated: Jan 31, 2006 | Document ID: 48262 |