Introduction; Pots Signaling - Patton electronics SmartNode Series Software Configuration Manual

28 • POTS port configuration

Introduction

This chapter provides an overview of SmartNode POTS ports and describes the tasks involved in configuring
POTS ports in SmartWare.
This chapter includes the following sections:
• Shutdown and enable POTS ports (see
• Configuration of common POTS port parameters (see
• POTS port configuration task list (see
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.

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 inter-
face card etc.).
Dialing on analog phones is accomplished by means of pulse or tone dialing. With pulse dialing the line (cur-
rent) 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 sup-
planted 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.
354
page 355)
page 356)
Port activation deactivation—POTS ports can only be con-
figured when in the down state. The first configuration task
explains how to disable and enable POTS ports for configura-
tion. 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.
SmartWare Software Configuration Guide
page 356)

Introduction