Configuration
transmitted to the far end AVA-E. The on-hook or off-hook information is then relayed to the telephone
switching equipment by the far end FXO unit. Tone dial DTMF tones are transferred transparently, pulse
dialing is not supported.
In an FXS to FXS configuration automatic ring-down is enabled. When the telephone at one end is off-
hook, the telephone at the other end rings automatically. If the always off hook option is enabled, no
ringing occurs.
CAUTION
Excessive ringing loads on the voice circuits can cause damage to the units! Old style telephones with
“bell” ringers will damage the equipment. Use newer phones with electronic ringers having a ringer
equivalence of 1.0B or less.
FXO
– The FXO mode is the inverse of the FXS mode. The FXO interface appears as a telephone instrument
to the attached equipment. When in FXO mode, the AVA-E’s signaling circuits are conditioned to detect an
incoming ring signal, representing an incoming call, and to provide a DC path (loop closure) to the PBX or
central office switch to indicate on-hook/off-hook status. When ringing is detected, the FXO end will send an
incoming call indication to the FXS unit at the far end, thus instructing it to ring its phone. When the far end
FXS unit detects an off-hook condition, it sends an off-hook indication to the near end FXO which then
provides an off-hook (loop closure) state to the telephone switching system. In this manner, the FXS/FXO
pair together make the two AVA-E units at the two ends of the line appear “transparent” to the operation of a
normal telephone line. Thus the user may establish the same type of telephone services over the circuit
derived through the use of the AVA-E multiplexers that he or she could by direct connection over a normal
telephone pair. In other words, the AVA-E multiplexer will not interfere, and will pass essentially
unchanged, the signaling normally present in a standard telephone line connection. FXO to FXO connections
are not allowed.
E&M
– In this mode, the AVA-E interfaces to the tie trunk port of a PBX, and provides a Type 1 E&M
signaling interface. This is a logic level type interface, where typically the PBX places battery voltage on the
M-lead to indicate an off-hook condition to the AVA-E, and the AVA-E in return, places a ground on the E-
lead to indicate a busy condition to the PBX. The E&M interface of the AVA-E is available on the eight wire
modular jack marked “E&M”, and provides for four-wire voice operation.
There are two modes of E&M operation. In normal mode the audio channel is always active and voice
transmission can occur with or without M-lead control.
In M-input mode, analog voice transmission will occur only when the M-lead is driven to -48v with respect
to E&M ground, or when the "PTT In" pin of the MIC/PTT interface is grounded.
MIC-PTT
– In this mode a Push-to-Talk Microphone (available from DCB) is connected to the front panel
MIC port. The audio output at the far end is controlled by internal jumper J4 .
Resetting Factory Defaults
The factory default settings for the AVA-E data and voice ports are as follows:
Serial Network Port (“
SYNC NETWORK
”):
Modem type Async
Rate
57.6 Kbps
Data Port (“
ASYNC DATA
”):
Rate
9600 bps
Parity
None (8N1)
Flow ControlNone
Transmit Timer
10ms
DCD to RxD holdoff 0 ms (DCD forced ON)
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