derek (08/20/82)
Thank you so much to all who replied to my query. Several questions have come up in response to all of the replies which I received. I will also summarize the replies received so far. I am trying to select a 300/1200 baud, auto-answer (with speed recog- nition), auto-dial modem for dialing Usenet with uucp, (unattended), and dialing other computers (with cu). The unit should also be able to act as a dial-in. Q: How important is tone dialing? It has been said that pulse dialing will not pass through the exchanges to remote PABX's. Q: Is a dial tone detection important when dialing out on centrex or is a time delay adequate? Q: What drivers are available for the different types of modems? If your system is equipped with an auto dialer, what is it? Does it dial Usenet automatically? I will summarized this list and post results. Summary of responses: The Racal-Vadic 3451PA and the Ventel 212+ seem to be the prime contenders based on the responses (most were about these units) and the price. The 3451 is pulse only whereas the 212+ is also touch tone (however, someone indicated that it's tone dialing is not reliable.) Neither has a dial tone detection circuit. Both run 300 baud (103) and 1200 baud (212) but the 3451 also has a 3400 protocol. The 3400 is more reliable, allowing RV to develop a 1200 baud acoustic coupler. Both units do auto bauding on answer but the 3451 requires a second rs232 line to indicate the speed. The 212+ rasises carrier when powered on (allowing Unix to open the line). This means a user MUST log out at the end of the session or Unix will never know about it. The 3451 requires an operating system hack to allow the user to open the line before carrier is raised. Ignore the Novation line of modems. Their 1200 baud is half duplex using 202 (not 212) protocol. This is a dying beast. The Anderson Jacabson 1259 and the Datatec 212a are very similiar in operation to the Racal Vadic 3451 but neither has the 3400 protocol. Other units which I have no information on and probably should be looked at are OZ225 (expensive but LOTS of features), Penril, Hayes 1200, and Cermetek 212a. It is possible to purchase your auto-dialer and modem seperately. DEC offers a DF03 pulse dialer with a manual switchable speed on the modem. Racal Vadic has a VA811 auto-dialer and 831 modem. Well, that is where I stand. Which would you choose? I do not know much more that what is displayed here. Some offer the capability to store frequently dialed numbers but that does not apply to my situation. If any information here is incorrect, please post an item to net.dcom so everyone will see it.
thomas (08/20/82)
We have a Vadic 3451a which does both tone dialing and dial-tone detection. However, we have been having problems with it hanging lately (holds the line off hook and all sorts of fun things). Round and round with the Vadic people, no end in sight. Assuming it works, though, it has great functionality. =Spencer
knutsen@sri-unix (08/30/82)
We used to have a vadic 300b autodialer, and recently
got a ventel 212+. A few points:
1) An OS hack is not really necessary for modems which dont always
raise carrier-detect. We just moved the pin on the plug
on the modem end of the cord from pin 8 (CD) to pin 9 (+12).
This did the trick. Actually our vadic had a mode which
supposedly kept CD up, but it went down for about
1/2 second as carrier was acquired. Just long enough for unix
to close the line. What would be best would be to have a
short drop as carrier was lost. Anybody do this?
2) Our ventel does have dial tone detect. An ampersand ('&') in the
number will wait for it.
3) My main complaint with the ventel is that it wont send the two
non-numeric tones ('#' and '*'). Is there a modem that will?
Our PBX uses these for billing.
The ventel seems to be working pretty well now, tho the
autobauding (it determines the speed from the tty line) sometimes
screws up when machine-done and our PBX takes a long time to connect,
resulting in occasional timeouts. We have uucp mods to allow returns
and delays to be specified in L.sys, but I dont think even this is
necessary, and we're standard otherwise.
Btw, I had to add a line to L-devices for 1200 baud, so we have
a "cul0" for 300 and a "cul1" for 1200. These are linked to the same
file in /dev, but have different speeds in L-devices. Sending a
return, delay, return to the dialer usually does the autobaud.
Andrew