TiVo Community Forums Archives - Has anyone had a successful call with back-to-back modems?

TiVoCommunity.com
(c)opyright 1995-2005 All rights reserved
indexcheckTC
This area is a static history of posts in the TiVo Community Forum Archive.
This archive history was made for the simple indexing of search sites like Google.

Pages:1

Has anyone had a successful call with back-to-back modems?
(Click here to view the original thread with full colors/images)

Posted by: KA6IRI

Are there any secrets to make this work? Does TiVo use an unauthenticated PPP, or is there a username and password the PPP server needs to accept?

Posted by: jmccorm

Actually, you ask an interesting question! An earlier post talked about inserting the strings necessary to drop the speed down. Imagine if you drop the speed down to 300 baud. This would survive recording and playback on a tape recorder. You could then use the tape recorded version of a TiVo session to 'home' in order to reverse engineer what goes on during a dial-in call. Assuming, of course, the ISP used will allow a 300 bps connection. This could be interesting....

Posted by: barebottoms

quote:
Originally posted by jmccorm:
You could then use the tape recorded version of a TiVo session to 'home' in order to reverse engineer what goes on during a dial-in call.

Seems it would be easier to look at the ppp dump.

Posted by: d18c7db

Actually you don't need to go as far as tape recording a 300 baud modem to figure things out. All I did is set up PPP to the Internet and then capture the packets. Much more elegant :-)

As for back to back modems, I haven't personally done it but I would be interested in the procedure. Unfortunately my TiVo has a fried modem (picks up the line, but then it says there is no dial tone).

In a previous thread on a similar topic someone suggested that you wire the two modems in series with a 9v battery. Not sure if this will work but it won't cause any harm either. Polarity should be irrelevant.

The only problem with that is that you cannot "ring" the other modem as you need to insert 80V AC or so on the line to "ring" but if you manually force the other modem to "pick up" you should be sweet.

Maybe a telco can verify if the battery is really needed. My gut would say not, as all you do is hook up the output impedance matching transformer of one modem to the other, you shouldn't need any external voltage on the line (ignoring the AC "ring" voltage).

A

[This message has been edited by d18c7db (edited 01-23-2001).]

Posted by: Mazzic

quote:
Originally posted by barebottoms:
Seems it would be easier to look at the ppp dump.

Aww, some people have to take all of the fun out of it. I mean it has to be take some effort these days to find a 300 baud modem! But your right a dump of the PPP activity should be easier.

------------------
-Mazzic
Has a 60GB drive with a 30 hour image on it. Wants the MFS expansion hack! :>

Posted by: A. Edgar Rube

quote:
Originally posted by KA6IRI:
Are there any secrets to make this work? Does TiVo use an unauthenticated PPP, or is there a username and password the PPP server needs to accept?

I'm working on getting this set up. I tried with some old Mac software, but couldn't create a user name long enough. The limit was 31 chars, and the TiVo sent a 33 char user. *grumble* Software with stupid limitations. . .

The TiVo sends a login that's something like this:
xxxxxxxxxxxxxxx.yyyyyyyy@tivo.net
x are the serial number
y are some sort of hash

The pass I don't remember.

If you get a PPP server set up, you should be able to see what login/pass your TiVo tries in the log files after letting it call once, then create an account. I wasn't paying close enough attention at the time to be sure the hash or the pass don't change each call. Maybe someone else can speak to that.

[This message has been edited by A. Edgar Rube (edited 01-23-2001).]

Posted by: KA6IRI

quote:
Originally posted by A. Edgar Rube:
I'm working on getting this set up. I tried with some old Mac software, but couldn't create a user name long enough. The limit was 31 chars, and the TiVo sent a 33 char user. *grumble* Software with stupid limitations. . .

When you got it to connect to your mac, would it connect using the "Test Phone Connection", or did you have to do a daily call? When I try the test call, the TiVo hangs up immediately after my computer answers and starts negotiating the carrier. Do I need to force my modem not to try to connect at 56K?

[This message has been edited by KA6IRI (edited 01-24-2001).]

Posted by: A. Edgar Rube

quote:
Originally posted by KA6IRI:
When you got it to connect to your mac, would it connect using the "Test Phone Connection", or did you have to do a daily call? When I try the test call, the TiVo hangs up immediately after my computer answers and starts negotiating the carrier. Do I need to force my modem not to try to connect at 56K?

I used the "Test Phone Connection." I remember having that behavior until I switched around some of the PPP server options. I'll try to get that machine booted up again today and see what they were. I'm pretty sure it was a problem when I turned on noauth.

More later. . .

Posted by: KA6IRI

Thanks. I'm having troubles getting enough of a connectino to trace the auth process so I know what user I need to allow.

Anyone know what's the best Linux PPP server, and how do I get it to give me a complete trace of the authentication exchange?

Posted by: HTH

quote:
Originally posted by Mazzic:
Aww, some people have to take all of the fun out of it. I mean it has to be take some effort these days to find a 300 baud modem!

I have a TRS-80 Acoustic Terminal that can do both 0.3 kbps and 0.11 kbps. Thermal paper output. Only thing is, it's hard to find telephones with handsets that will fit it these days.

------------------
http://www.war-of-the-worlds.org/tivo/HTH.gif

Posted by: lbroadfield

quote:
Originally posted by d18c7db:
The only problem with that is that you cannot "ring" the other modem as you need to insert 80V AC or so on the line to "ring" but if you manually force the other modem to "pick up" you should be sweet.

Change the other modem's init string to wait infinitely for originate carrier (one of the s registers) and then go off hook in answer mode.

Change the TiVo's dial string to be "RING<cr><lf>".

------------------
--Laird

Posted by: KA6IRI

quote:
Originally posted by lbroadfield:
Change the other modem's init string to wait infinitely for originate carrier (one of the s registers) and then go off hook in answer mode.

Change the TiVo's dial string to be "RING<cr><lf>".

You've had success with this on a TiVo?

Posted by: nextguard2

quote:
Originally posted by HTH:
I have a TRS-80 Acoustic Terminal that can do both 0.3 kbps and 0.11 kbps. Thermal paper output. Only thing is, it's hard to find telephones with handsets that will fit it these days.

I think the traditional way is to use a pay phone with a radioshack tone dialer so you dont leave prints. http://www.avsforum.com/ubbtivo/smile.gif

------------------
NextGuard = Paul from Atlanta

Posted by: alhaz

Don't be silly.

You can't just connect two modems to eachother. You need an oscilating current on the line in order to make the connection and maintain communication. the line must have particular qualities. This requires what is refered to in the telecom industry as a "ring-down box" or sometimes as a phone line simulator. (I used to troubleshoot OS/2 based voicemail systems for a living, they were invaluable to my work)

They are *Not cheap. the cheapest of them are a couple hundred dollars. There are two reasons they are expensive.

1: Low demand

2: They're a telecom device, so you use exponents to calulate the MSRP vs. cost of manufacture.

If you're technologically inclined and handy with a soldering iron, you can build your own for $30 or so in parts, though radioshack may not have all of what you need. There are free schematics on the web.

Also, don't expect to get a 33.6 connection, it's hard to pretend you're the phone company with a little box of transformers & whatnot. I usually get around 22k between 56k modems with mine.

You're much better off doing PPP to a linux box over the DSS port.

[This message has been edited by alhaz (edited 02-01-2001).]

[This message has been edited by alhaz (edited 02-01-2001).]

Posted by: janedoe4997

quote:
Originally posted by A. Edgar Rube:
The TiVo sends a login that's something like this:
xxxxxxxxxxxxxxx.yyyyyyyy@tivo.net
x are the serial number
y are some sort of hash

The yyyyyyyy was a timestamp. It was the exact time of day of your call
in Greenwich Mean Time, in seconds since January 1st 1970.

You can check what time it is now under those rules by entering:

tivosh

clock seconds

exit

Posted by: KA6IRI

So here's the deal: I already have a small phone system in my house that includes a couple of analog ports for answering machines, faxes, etc. I can set the TiVo's dialing prefix to dial the extension of the other analog port, and have that port connected to a modem in my server. The server connects to the DSL. If I can get the server to answer the call, accept the xxxxxxxxxxxx.yyyyyyyy@tivo.net as a valid client, and establish a PPP session with the TiVo, then I'm set. And I don't have to worry about 2.0 breaking my setup. I may not get great speeds, but at least I wouldn't be tying up my phone line.

So anyone, please, what does my server need to be running? Does the TiVo do a PAP, or CHAP auth, or something else? Is TiVo's RADIUS server reachable on the net so I could refer the auth request to it?

Posted by: lbroadfield

quote:
Originally posted by alhaz:
Don't be silly.

You can't just connect two modems to eachother.

Eh? Of course you can; in fact, a plain old $5.95 tone (okay, my prices may be a little out of date) with the switch set to "continuity" rather than "tone" will power a line sufficiently for 4 or 5 extensions to work. This is a known and supported use. "All 77 Series Tone Generators provide the four basic functions of tone signal, continuity testing, talk battery supply, and line polarity confirmation."

In that mode, all they're really doing is putting a 9v battery across the line; you can do the same thing with... a 9v battery.

quote:
You need an oscilating current on the line in order to make the connection and maintain communication. the line must have particular qualities.

Not at all. In fact, off-hook talk battery from the telco is typically a straight about 8 volts DC (this will vary anywhere from 2 to 12 depending on the distance from the CO, the impedance of the sets connected, etc.)

On hook is a healthy 48VDC, but at low total power; the added impedance of the off-hook set clips it down to 8.

Ring voltage is where it gets interesting; a ring signal is a 20Hz 105VAC signal, in a one second on, two seconds off pattern.

quote:
This requires what is refered to in the telecom industry as a "ring-down box" or sometimes as a phone line simulator. (I used to troubleshoot OS/2 based voicemail systems for a living, they were invaluable to my work)

A ringdown box is key to that sort of work, because you need to simulate the actual behaviour of a line, including presenting dialtone, accepting digits (or simulating their acceptance wth a delay and dialtone break) nd delivering ring voltage to the other end.

However, if all you need to do is establish voice carrier between two otherwise self-powered sets, all you need is a 9v battery you can change every couple of months.

quote:

[...]
You're much better off doing PPP to a linux box over the DSS port.

Possibly true, but for entirely different reasons.

(Age and experience will always defeat youth and enthusiasm. :-) )

------------------
--Laird

Posted by: soundguy

>>(Age and experience will always defeat youth and enthusiasm. :-) )

I believe the correct quote is "age and treachery"... http://www.avsforum.com/ubbtivo/smile.gif

------------------
Patrick Callahan
Check out www.themothership.net for links to the latest PTV technologies!