asterisk users - Dec 2008 - Sip Node w/ 4 wire audio & AT command set call supervision

I have several discontinued Sierra Wireless MP775 mobile GSM/EDGE radio
modems. These devices were originally installed in emergency vehicles to
provide data and voice access along with GPS reporting. They have external
RF connections for GSM/EDGE and GPS signals. The baseband side includes four
wire audio, RS-232 serial, USB and some parallel digital I/O for panic
switches etc. GSM voice connections are established by sending AT commands
via the RS-232 serial or USB ports and utilizing a handset connected to the
four-wire audio jack. Here is a link to the Sierra Wireless web pages for
the MP775.

 

http://www.sierrawireless.com/support/mp775.aspx

 

My interest comes in finding an inexpensive way to connect an Asterisk PBX
or similar system to the PSTN via GSM when POTS and Internet service isn't
available or is too costly to connect. In my case, I'm considering building
a house at the end of a long unpopulated stretch of dead end road and the
cost of trenching and cabling from the nearest telco POP is prohibitive.

 

I would like to find a way to connect these modems to my network so they
appear as a SIP FXS device. This would require a device generating/reading
AT commands and passing baseband audio on the front end and SIP emulation on
the backend. I'm sure there must be a way to do this with a pc but to
minimize power consumption; I would prefer to use something like a small
single board computer with a Geode processor. The latter, having multiple
RS-232 and audio ports, ought to be capable of handling at least two of the
MP775's.

 

Has anyone seen any hardware, software or combination that would allow me to
accomplish such an interface?

 

Regards,

George

 

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL:
http://lists.digium.com/pipermail/asterisk-users/attachments/20081206/e3499697/attachment-0001.htm

On Dec 6, 2008, at 7:55 AM, George Bean wrote:
> I have several discontinued Sierra Wireless MP775 mobile GSM/EDGE  
> radio modems. These devices were originally installed in emergency  
> vehicles to provide data and voice access along with GPS reporting.  
> They have external RF connections for GSM/EDGE and GPS signals. The  
> baseband side includes four wire audio, RS-232 serial, USB and some  
> parallel digital I/O for panic switches etc. GSM voice connections  
> are established by sending AT commands via the RS-232 serial or USB  
> ports and utilizing a handset connected to the four-wire audio jack.  
> Here is a link to the Sierra Wireless web pages for the MP775.
>
> http://www.sierrawireless.com/support/mp775.aspx
>
> My interest comes in finding an inexpensive way to connect an  
> Asterisk PBX or similar system to the PSTN via GSM when POTS and  
> Internet service isn?t available or is too costly to connect. In my  
> case, I?m considering building a house at the end of a long  
> unpopulated stretch of dead end road and the cost of trenching and  
> cabling from the nearest telco POP is prohibitive.
>
> I would like to find a way to connect these modems to my network so  
> they appear as a SIP FXS device. This would require a device  
> generating/reading AT commands and passing baseband audio on the  
> front end and SIP emulation on the backend. I?m sure there must be a  
> way to do this with a pc but to minimize power consumption; I would  
> prefer to use something like a small single board computer with a  
> Geode processor. The latter, having multiple RS-232 and audio ports,  
> ought to be capable of handling at least two of the MP775?s.
>
> Has anyone seen any hardware, software or combination that would  
> allow me to accomplish such an interface?
>
> Regards,
> George
I've not heard of any such hardware/software combination to do this,  
so I apologize for the semi-useless reply.  However, I'd be very  
interested in any solutions you come up with, since I've got a few  
similar older WaveCom modem devices which probably do mostly the same  
thing - I think I picked them up for about $6 each on eBay, and I see  
a few there now for $30-$50 range.  I bought them just for SMS, but  
they are fully-functioning GSM phones if you want to wire up the right  
pins on the connector to speaker/microphone parts.

You also should take a look at eBay which has a number of SIP-to- 
mobile (SIP to GSM, SIP to CDMA) conversion units.  Type "sip gsm" in
the search term box.  There's even one for $150 that seems to use  
bluetooth to connect SIP to Bluetooth phones (which can be done  
directly with Asterisk, though it may take some significant fist- 
slamming to get the drivers all set up correctly.)  Maybe you have an  
older Bluetooth phone to use the lower-cost option, or maybe the  
integrated SIP/GSM system makes sense.  If you're going to spend the  
money for a purpose-built solution, you might want to make sure that  
whatever gateway you get also supports SMS in some fashion.  Some of  
us are waiting for the drivers to get Asterisk to talk directly to the  
PORTech devices for send/receive SMS capability.  (hint, hint)

If you take the modem/soundcard route, perhaps there are some useful  
cards or things here -  http://www.ramseyelectronics.com/ - I haven't  
dug through, but they seem to have lots of small-end hacker-friendly  
bits and pieces which might do some of the line-level conversions you  
would require. You might connect directly to an Asterisk-driven  
soundcard, or you might use an FXO/FXS type conversion as well and  
connect to a single-line analog PC card that works with DAHDI/Zaptel.   
Get out the soldering iron!

JT

---
John Todd
jtodd at digium.com        +1-256-428-6083
Asterisk Open Source Community Director

Google Multitech CallFinder GSM out of Minnesota if you want a common
off the shelf product.  GSMA.org was using their product with FXO/FXS
for backup purposes.

 

I recall they have a GSM to FXO/FXS, and I thought they had GSM to H323.

 

I also found a European company that made high end (24+) GSM banks to
FXO/FXS but can't recall the name.

 

 

 

________________________________

From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of George
Bean
Sent: Saturday, December 06, 2008 8:56 AM
To: asterisk-users at lists.digium.com
Subject: [asterisk-users] Sip Node w/ 4 wire audio & AT command set
callsupervision

 

I have several discontinued Sierra Wireless MP775 mobile GSM/EDGE radio
modems. These devices were originally installed in emergency vehicles to
provide data and voice access along with GPS reporting. They have
external RF connections for GSM/EDGE and GPS signals. The baseband side
includes four wire audio, RS-232 serial, USB and some parallel digital
I/O for panic switches etc. GSM voice connections are established by
sending AT commands via the RS-232 serial or USB ports and utilizing a
handset connected to the four-wire audio jack. Here is a link to the
Sierra Wireless web pages for the MP775.

 

http://www.sierrawireless.com/support/mp775.aspx

 

My interest comes in finding an inexpensive way to connect an Asterisk
PBX or similar system to the PSTN via GSM when POTS and Internet service
isn't available or is too costly to connect. In my case, I'm considering
building a house at the end of a long unpopulated stretch of dead end
road and the cost of trenching and cabling from the nearest telco POP is
prohibitive.

 

I would like to find a way to connect these modems to my network so they
appear as a SIP FXS device. This would require a device
generating/reading AT commands and passing baseband audio on the front
end and SIP emulation on the backend. I'm sure there must be a way to do
this with a pc but to minimize power consumption; I would prefer to use
something like a small single board computer with a Geode processor. The
latter, having multiple RS-232 and audio ports, ought to be capable of
handling at least two of the MP775's.

 

Has anyone seen any hardware, software or combination that would allow
me to accomplish such an interface?

 

Regards,

George

 

 




-----------------------------------------
Disclaimer:

This e-mail communication and any attachments may contain
confidential and privileged information and is for use by the
designated addressee(s) named above only.  If you are not the
intended addressee, you are hereby notified that you have received
this communication in error and that any use or reproduction of
this email or its contents is strictly prohibited and may be
unlawful.  If you have received this communication in error, please
notify us immediately by replying to this message and deleting it
from your computer. Thank you.
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
http://lists.digium.com/pipermail/asterisk-users/attachments/20081207/7588c1a2/attachment.htm