TECHNICAL BULLETIN #137 - Rev 1.10 (9/03/96)

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TITLE   : Caller ID Frequently Asked Questions
PRODUCT : Procomm Plus 4.x, 3.x
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Q: When does the Caller ID information get sent from the Telephone Company?

A: Caller ID information should get sent 300ms after the first ring burst,
   and end as early as 475ms prior to the second ring burst.  If a person
   or a device picks up the line prior to the second ring, the Caller ID
   information can become lost or corrupt.

Q: Can a regular modem be used to get Caller ID information?

A: Any modem supporting Bell 202 or CCITT v.23 could be altered to read
   Caller ID information.  The RI bit may be used on a modem to indicate
   when to monitor the phone line for CND information.  After the RI bit
   sets, indicating the first ring burst, the host waits for the RI bit to
   reset. The host then configures the modem to monitor the phone line for
   CND information. Unless the modem has been specially built to read CND
   information, it will have to be altered so that it can receive
   information without having to negotiate for a carrier.

Q: What is the difference between Calling Number Delivery and Calling Name
   and Number Delivery?

A: In Calling Number Delivery (or Basic Caller ID as it is better known),
   only the date, time, and phone number of the person calling you is sent
   from the telephone company.  In Calling Name and Number Delivery (or
   Extended Caller ID),  the date, time, phone number, and the name of the
   subscriber will be sent from the telephone company.  Most new modems
   support both forms of Caller ID.

Q: Caller ID always shows the main number where I work.  It never shows
   the line into my office.  Why?

A: Since CND information comes from the telephone company and is then
   transmitted to the called party, the phone number displayed will be the
   phone number of the line out that is used.  In a PBX system, there are
   often several internal phone lines that share a set of outgoing "trunk"
   lines.  The phone number of these outgoing lines that are being shared
   are the numbers that will show up on the called party's Caller ID
   display device.

Q: I have forwarded my calls to another number, but Caller ID never shows
   the number of the calling party.  It always shows my phone number.  Is
   there any way to correct this?

A: Generally, the number reported is that of the last phone to forward the
   call. Again, there are some telephone company differences.  If the
   forwarding is done by customer owned equipment, there is no way of
   telling, but will probably be the last calling number.  Any work around
   for this will have to be asked of the local telephone company.

ERROR MESSAGES

Q: What does ANONYMOUS CALL mean?

A: The calling party has the capability to make a call and request that
   the telephone company refrain from sending the Caller ID information to
   the called party.  When this happens, ANONYMOUS CALL is displayed on
   the Caller ID display.  Instead of sending the normal Caller ID
   information, it sends an ASCII "P" to indicate that a privacy mechanism
   has been enacted on the side of the calling party.

Q: What does OUT OF AREA mean?

A: This message appears on Caller ID displays when the calling party
   either does not have Caller ID in their area, or it is a long distance
   phone call, and the long distance carriers do not send CND information
   to each other.

Q: What does NO DATA SENT mean?

A: This indicates that Caller ID unit detected an incoming ring, but one
   of the following conditions caused the CND information to be incorrect:

   * No CND information was sent from the telephone company because the
     line was picked up too quickly.

   * The checksum word did not match the modulo 256 of the CND
     information.

   * The CND information was cut off due to the line being picked up too
     quickly.

Q:  What does UNAVAILABLE mean?

A:  This message appears on Caller ID displays when the calling party
    either does not have Caller ID in their area, or it is a long distance
    phone call, and the long distance carriers do not send CND information
    to each other.

Q:  What does DATA ERROR # xxxx mean?

A:  This is a vendor specific error message indicating that something was
    corrupt in the CND information that was received from the phone
    company. You will need to refer to the documentation that came with
    the Caller ID device.

Q:  What does BUFFER FULL mean?

A:  This is a vendor specific error message that may mean that the device
    has a limited buffer space and the device is either losing the
    earliest call records or has stopped recording new calls

ADDITIONAL TECHNICAL INFORMATION

If you are using the World Wide Web, you can obtain additional technical
information on Caller ID from:

   http://www.eff.org/pub/Security/Caller_ID

NOTE: This information is provided "as is".  The URL listed above is
subject to change.

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           Copyright (c) 1996 Quarterdeck  All rights reserved.
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