kujanpa@ccu.umanitoba.ca (02/13/91)
Hi everyone. A friend has been having problems
with prank phonecalls. He was wondering if there is a
circuit/schematic that would display the calling (ie.
incoming) number. I know there are commercial units that
will do this, but he is a broke EE student.
The questions are:
1) Can this be easily done?
2) What wires are required, and what signals are on these
wires.
3) What protocol is used for this?
Thanks in advance!
Bob Kujanpaa
Please respond vi e-mail.
kujanpa@ccu.UManitoba.CArbrink@hubcap.clemson.edu (Rick Brink) (02/16/91)
OK, we all know what Caller ID is by now. How about some quickminded programmer take the sting out of this for everyone. Why can't someone do the code to use one's computer modem to do the caller ID inquiry. If it's a matter of the switchhood voltage drop, a simple circuit should take care of that. Surley these $125 boxes are just expensive tone encoders with a little memory. I'd register a few dollars for a shareware program that does that. (I think ol' ma' bell may have smelled this one, there is probably some very explicit reason why it can't be done, just the way they wanted it....)
kahhan@bnr.ca (02/17/91)
In article <13147@hubcap.clemson.edu> rbrink@hubcap.clemson.edu (Rick Brink) writes: >OK, we all know what Caller ID is by now. How about some quickminded programmer >take the sting out of this for everyone. > >Why can't someone do the code to use one's computer modem to do the caller ID >inquiry. If it's a matter of the switchhood voltage drop, a simple circuit >should take care of that. Surley these $125 boxes are just expensive tone >encoders with a little memory. I'd register a few dollars for a shareware >program that does that. > >(I think ol' ma' bell may have smelled this one, there is probably some very >explicit reason why it can't be done, just the way they wanted it....) One problem with using the modem to pick off the caller ID number is that most computer modem operating at 1200 BPS use the 212 standard, while caller ID from the telcos conforms to the old 202 standard. The modulation schemes are entirely different, with 202 being FSK, while 212 is PSK. Unless your modem is based on a DSP chip which can be reprogrammed via software off the floppy disk, this does not represent a viable solution. On the other hand, building a decoder is not that difficult. Standard ICs are readily available (AMD has their "world chip") which can implement the 202 standard. I would expect that we'll soon be seeing kits and or low cost devices available shortly. In the near term, this could be a good business opportunity, until the Japanese ramp up production and start selling them for $15. -- ---------------------------------------------------------------------------------- Larry Kahhan - NRA, NRA-ILA, CSG, GOA, GSSA | The opinions expressed here do | not necessarily represent the | views of the management. ----------------------------------------------------------------------------------
henry@zoo.toronto.edu (Henry Spencer) (02/20/91)
In article <1991Feb12.224124.12551@ccu.umanitoba.ca> kujanpa@ccu.umanitoba.ca writes: > Hi everyone. A friend has been having problems >with prank phonecalls. He was wondering if there is a >circuit/schematic that would display the calling (ie. >incoming) number... First he needs to call the phone company and ask if caller-ID is available in his area, how much it will cost, and how long it will take to have it activated. It is *not* free. -- "Read the OSI protocol specifications? | Henry Spencer @ U of Toronto Zoology I can't even *lift* them!" | henry@zoo.toronto.edu utzoo!henry