Erik Jacobs
2006-Jul-14 08:07 UTC
[asterisk-users] "Legacy" analog data modems and Asterisk
I did some poking around on the Googleweb and was unable to find a concise answer to my situation. I have some guesses and some theories about what will work and what might not work, but I'm sure that others have followed this path before. Currently we have a large number of customers that we support via analog modem. To make a long story short, it's very difficult for these customers to be able to provide VPN access into their networks of our hardware due to various security and large-company bureaucracy issues. Therefore, the modem connections remain. We are considering an Asterisk-based PBX for an upgrade to our existing Panasonic DBS72, which is a fine system but simply doesn't cut it for the things we need to do. However, this poses the problem of what to do with the modems. Preface the following with this: We have *0* desire to terminate calls via IP. We're using Asterisk for the ease of adding phones locally and remotely, not because we want to save money via IP calling (which would be improbable, as our 6 PSTNs have unlimited local and long distance + DSL). Options (in no particular order): 1) Connect Asterisk to existing 6 PSTN lines using FXO. Connect existing modems to Asterisk using FXS. Data speeds will probably be sub 14.4k, which is not acceptable. 2) Upgrade PSTN to PRI. Connect Asterisk to PRI and connect modems to FXS. Anyone have an idea about the potential data speeds here? 3) Connect Asterisk *AND* modems to PSTN using splitters. Does anyone know what happens if someone is using a PSTN with the modem and Asterisk tries to use an FXO? Is Asterisk "smart" enough to detect that the PSTN is currently in use? Or is it like your little sister and it will pick up the phone while you're dialed into a BBS and knock you offline.... (ahh, those were the days). 4) We make PPP connections to our customers with the existing modems (for the most part), so I'm not sure that there would be any way to somehow hook the modems up to the Asterisk box and have the Asterisk make the connection. This would very likely involve some extraordinarily complex routing tasks and, as we're looking to a 3rd party Asterisk PBX provider, I don't think we'll have the access to the guts of the hardware to do this. 5) The most simple and least elegant -- unplug the phone line you want to use for modem from the FXO and plug it into your modem. Que sera, sera. Sorry that my first post is a huge plop, but it's an interesting situation that I've been going back and forth about for a while. Plus, Asterisk sure beats a $20k Altigen setup. Erik Jacobs Project Engineer erik.jacobs@crystalcc.com
Don Pobanz
2006-Jul-14 08:43 UTC
[asterisk-users] "Legacy" analog data modems and Asterisk
Erik Jacobs wrote:> Options (in no particular order): > > 1) Connect Asterisk to existing 6 PSTN lines using FXO. Connect existing > modems to Asterisk using FXS. Data speeds will probably be sub 14.4k, which > is not acceptable.Yes, this would connect modems at slow speeds (or not at all) due to the additional A/D conversion into * and the D/A conversion out of * to interface the pots lines.> 2) Upgrade PSTN to PRI. Connect Asterisk to PRI and connect modems to FXS. > Anyone have an idea about the potential data speeds here? >We have been doing this and it has worked well for us. Because we are dialing to another modem that is on a pots line and not directly into a modem bank on another digital T1 like ISP would have, the speeds will never approach the upper ends of a 56k modem speeds. From my foggy memory I believe we were seeing around 28k.> 3) Connect Asterisk *AND* modems to PSTN using splitters. Does anyone know > what happens if someone is using a PSTN with the modem and Asterisk tries to > use an FXO? Is Asterisk "smart" enough to detect that the PSTN is currently > in use? Or is it like your little sister and it will pick up the phone > while you're dialed into a BBS and knock you offline.... (ahh, those were > the days).Asterisk is NOT smart enough to know the line is already in use and so avoid using it.> > 4) We make PPP connections to our customers with the existing modems (for > the most part), so I'm not sure that there would be any way to somehow hook > the modems up to the Asterisk box and have the Asterisk make the connection. > This would very likely involve some extraordinarily complex routing tasks > and, as we're looking to a 3rd party Asterisk PBX provider, I don't think > we'll have the access to the guts of the hardware to do this.??> 5) The most simple and least elegant -- unplug the phone line you want to > use for modem from the FXO and plug it into your modem. Que sera, sera.Yes, this unsophisticated way would work. However if you go this route, get one of the A/B switches and just press A for modem or B for *. I did this at home for a while! Don Pobanz
At 08:07 AM 7/14/2006, you wrote:>3) Connect Asterisk *AND* modems to PSTN using splitters. Does anyone know >what happens if someone is using a PSTN with the modem and Asterisk tries to >use an FXO? Is Asterisk "smart" enough to detect that the PSTN is currently >in use? Or is it like your little sister and it will pick up the phone >while you're dialed into a BBS and knock you offline.... (ahh, those were >the days).Can you get distinctive ring on those lines and have one of those fax splitters send the modem calls to the modem? Ira
Brian Vincent (C)
2006-Jul-17 10:53 UTC
[asterisk-users] "Legacy" analog data modems and Asterisk
I think an easy solution for you might be along the lines of #3 but using something like one of these devices: http://www.command-comm.com/products.html The ComSwitch 3.0, 5500, and 7500 are all "exclusionary" devices. If you're dialing outbound through it, Asterisk won't be allowed to pick up the line. It sounds like you're in a small office and something like that would work. ------------------- Brian Vincent Copper Mountain Telecom vincentb@coppercolorado.com -----Original Message----- From: asterisk-users-bounces@lists.digium.com [mailto:asterisk-users-bounces@lists.digium.com] On Behalf Of Erik Jacobs Sent: Friday, July 14, 2006 9:07 AM To: asterisk-users@lists.digium.com Subject: [asterisk-users] "Legacy" analog data modems and Asterisk I did some poking around on the Googleweb and was unable to find a concise answer to my situation. I have some guesses and some theories about what will work and what might not work, but I'm sure that others have followed this path before. Currently we have a large number of customers that we support via analog modem. To make a long story short, it's very difficult for these customers to be able to provide VPN access into their networks of our hardware due to various security and large-company bureaucracy issues. Therefore, the modem connections remain. We are considering an Asterisk-based PBX for an upgrade to our existing Panasonic DBS72, which is a fine system but simply doesn't cut it for the things we need to do. However, this poses the problem of what to do with the modems. Preface the following with this: We have *0* desire to terminate calls via IP. We're using Asterisk for the ease of adding phones locally and remotely, not because we want to save money via IP calling (which would be improbable, as our 6 PSTNs have unlimited local and long distance + DSL). Options (in no particular order): 1) Connect Asterisk to existing 6 PSTN lines using FXO. Connect existing modems to Asterisk using FXS. Data speeds will probably be sub 14.4k, which is not acceptable. 2) Upgrade PSTN to PRI. Connect Asterisk to PRI and connect modems to FXS. Anyone have an idea about the potential data speeds here? 3) Connect Asterisk *AND* modems to PSTN using splitters. Does anyone know what happens if someone is using a PSTN with the modem and Asterisk tries to use an FXO? Is Asterisk "smart" enough to detect that the PSTN is currently in use? Or is it like your little sister and it will pick up the phone while you're dialed into a BBS and knock you offline.... (ahh, those were the days). 4) We make PPP connections to our customers with the existing modems (for the most part), so I'm not sure that there would be any way to somehow hook the modems up to the Asterisk box and have the Asterisk make the connection. This would very likely involve some extraordinarily complex routing tasks and, as we're looking to a 3rd party Asterisk PBX provider, I don't think we'll have the access to the guts of the hardware to do this. 5) The most simple and least elegant -- unplug the phone line you want to use for modem from the FXO and plug it into your modem. Que sera, sera. Sorry that my first post is a huge plop, but it's an interesting situation that I've been going back and forth about for a while. Plus, Asterisk sure beats a $20k Altigen setup. Erik Jacobs Project Engineer erik.jacobs@crystalcc.com _______________________________________________ --Bandwidth and Colocation provided by Easynews.com -- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users ______________________________________________________________________________________________________________ Confidentiality Warning: This message and any attachments are intended only for the use of the intended recipient(s), are confidential, and may be privileged. If you are not the intended recipient, you are hereby notified that any review, retransmission, conversion to hard copy, copying, circulation or other use of this message and any attachments is strictly prohibited. If you are not the intended recipient, please notify the sender immediately by return e-mail, and delete this message and any attachments from your system. Thank you. ______________________________________________________________________________________________________________