lairdb@crash.cts.com (Laird P. Broadfield) (01/18/91)
In <16074@accuvax.nwu.edu> heiby@mcdchg.chg.mcd.mot.com (Ron Heiby) writes: >celoni@cunixf.cc.columbia.edu (Jim Celoni) writes: >>A caveat about the Universal Card: the magnetic stripe has the credit >>card number, not calling card number, so if you swipe it into a public >>phone, your credit card will be billed *by whatever carrier the phone >>wants to use*, and even if it's AT&T you won't get the 10% off. >I don't think that this is accurate. I believe that the stripe >contains both numbers on it. I believe this because when traveling I was reading this thread, and realized I had the equipment available from a recent R&D to answer this. Here's the deal: Remember that the card is a credit card; it just happens to come with a calling card number. The stripe data looks perfectly normal for a credit card, with all the usual ISO7813 field info filled in on both track 1 (6 bit +1 parity alphanumeric) and track 2 (4 bit +1 parity numeric). The ISO standards allow for some "discretionary data" up to the capacity of the stripe, following the required stuff on each track. My U-card has no discretionary data on track 2, but has the letters "ZZA" followed by my calling card number (without the PIN) in the track 1 discretionary area. This may tie in with Jim's U-rep saying that "not all phones are programmed to read this yet"; maybe ZZA is a magic flag meaning "a phone card number follows" and the machines need to be told to look for it and use it if it's there. Laird P. Broadfield UUCP: {akgua, sdcsvax, nosc}!crash!lairdb INET: lairdb@crash.cts.com