282 POTS
Port
Configuration
29 POTS PORT CONFIGURATION
This chapter provides an overview of SmartNode POTS ports and describes the tasks involved in configuring
POTS ports in SmartWare. For detailed information on syntax and usage guidelines for the commands listed
under Configuration Tasks refer to Chapter ???, “???”, in the SmartWare
Command Reference Guide.
This chapter includes the following sections:
•
Introduction
•
Shutdown and Enable POTS ports
•
Configuration of Common POTS Port Parameters
•
POTS port configuration Task List
29.1 Introduction
POTS stands for "Plain Old Telephone System" and is an acronym for analog telephony. Even though
POTS is seen as old technology it still plays an important part in today's telecommunications
networks. There are still a large number of analog phone sets in use worldwide and will do so in the
future. These analog devices, be they phones, facsimile machines and the like, represent a large
investment and it is desirable to have the technical means to hook such devices to a Voice over IP
enabled network. Inalp’s IC-4ab POTS interface card for the 2000 series SmartNodes provides 4
POTS FXS ports for hooking up 4 analog phone sets (or other analog devices) to the VoIP gateway
functionality of the SmartNode.
29.1.1 POTS Signaling
The signaling procedure used on POTS ports is different throughout different countries, but the basic
idea is to use the POTS line itself as a current loop which signals off-hook and on-hook of the
handset. Going off-hook establishes a connection between the phone and whatever is on the other
side (CO switch, IC-4ab interface card etc.).
Dialing on analog phones is accomplished by means of pulse or tone dialing. With pulse dialing the
line (current) is modulated in an on/off scheme according to the digit dialed; the digit 5 for instance
causes 5 current interruptions on the line (0 would cause 10 of these interruptions). This kind of
signaling has long been supplanted by tone (frequency) dialing and thus most analog phones in use
today do not support it anymore. Therefore pulse dialing is not supported by the IC-4ab interface
card.
Frequency or tone dialing uses DTMF tones to signal the digits 0 through 9, # and *. There are 4
lower and 4 upper frequencies and combining 1 frequency of each group to a dual tone pair signals a
specific digit. It is this signaling scheme that is supported by the IC-4ab. If unsure whether a phone
supports pulse or tone dialing (or both) simply hook such a phone to the (properly configured) IC-
4ab and dial any number – pulse dialing will be audible since it is in most cases done with relays.
29.2 Warnings
Port activation deactivation
POTS ports can only be configured when in the down state. The first configuration task explains how
to disable and enable POTS ports for configuration. When the port is down all active calls on the port
are dropped. This operation must only be performed during planned down times.
Connector Pinout and Short circuits
The ports of the IC-4ab use pins 2 and 3 on an RJ-11 jack.
Software Configuration Guide Release 2.10, Revision 1.00
Summary of Contents for SmartWare Release 2.10
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