The first expansion cabinet interface card (FXINT–XSRV) in an Impact FX system has two options slots, both of
which can have 2 DTMF receiver cards, allowing you to add up to 16 additional DTMF receivers.
The IST board provides onboard ring generators so there is no need for external ring generators.
The system sends a broken dial tone to an IST station to indicate message waiting; however, a message waiting
light is only available to stations on a FXISTM–16 board.
Determining The Board Configuration
Use the following specifications to determine the maximum number of station boards and DTMF receivers you
need.
•
Each 12-station circuit board supports up to 12 telephones. (It will actually support 24 telephones—two
telephones at each port sharing a common intercom number.)
•
You can bridge up to two industry-standard telephones at one station port as long as you do not exceed a
combined ringer equivalence number, or REN, of 2.0. (Remember, with two telephones at the same port,
they share a common intercom number.)
•
Each DTMF receiver allows one industry-standard telephone to dial at a time. (The number of DTMF
receivers that you need in the system will depend upon how active the industry-standard telephones will be at
the site.)
•
The Services board provides one onboard DTMF receiver, the FXINT–MAUX provides 8 onboard DTMF
receivers, and the FXAUX2–16 provides 16 onboard DTMF receivers. Further, you can add up to three
DTMF receiver cards to any auxiliary board to provide an additional 12 DTMF receivers over any onboard
support provided by the Auxiliary board, or add one DTMF card to the Interface board. (However, adding
these cards prevents you from adding other option cards such as communications cards for serial data
transfer and synchronizing cards for T1/E1 operation).
Based upon the above specifications, a fully-equipped Impact FX system with a minimum of one line board and
no auxiliary board will support 60 industry-standard telephones with only one telephone dialing at a time (five
12-station boards times 12 station ports per board). If you bridge extensions, the IST total increases to 120
telephones with two telephones per station port sharing the same extension number—still with only one telephone
dialing at a time.
With an Auxiliary board, you can increase the simultaneous dialing allowances. The following table details the
available simultaneous dialing combinations. Remember, the services board always provides one DTMF receiver.
Simultaneous IST Dialing Allowed
Auxiliary Board
Product Code
With Auxiliary Board
Interface
With Auxiliary Board Plus DTMF Receiver Card
One Card
Two Cards
Three Cards
FXINT–MAUX
9
13
FXAUX2–16
17
17
25
29
*The Services board always provides one DTMF receiver.
2 – Installing The IST Board
IMI89–268
Installing The IST Station Board
