VOIP
Hardware
PSTN gateways
I tried out a Linksys SPA-400 with 3 PSTN analog phone lines and an Asterisk server running on a recycled PC. It probably works fine as intended, in an all Linksys system but I was never able to get it to work reliably with Asterisk. The irony is that the SPA-400 runs Linux and Asterisk internally.
You can download the source tarball from the Linksys site.
version 1.0.0.2
It's based on Monta Vista Hardhat Linux
- MIPS processor
- ?? Flash
- ?? RAM
- Linux 2.4 kernel
- Busybox
- Asterisk PBX software
- thttpd
- /usr/sbin/lightbox controls LED's
- dropbear ssh
After a few months of wrestling with it, we bought a TDM-400 and sold the SPA-400 on eBay.
Digium X100P
These are fine if you only need one line, cheap on ebay.
Digium TDM400
This is the card I am working with now. It's great.
Sipura SPA3000
I'd like to try one of these as a single line solution.
I have a SPA3102 now that I picked up for the Chintimini Wireless Project.
Software
Asterisk -- works well but pretty complicated for small installations. I have some set up notes here Asterisk.
Freeswitch -- http://www.freeswitch.org/
I am testing a set up on 8track
Kirk Bailey is experimenting with pfSense (http://pfSense.com/) which is a FreeBSD based firewall project. It is intended for embedded systems such as the Soekris. pfSense has a package management system and there is now a FreeSwitch package. I am going for a file server based solution right now so this is on hold for me.
Asterisk
You might want to use an IDE/CF adapter that can hold two CF cards. This way you could stick in a smaller second card -say- 32 or 64MB and mount stuff like /etc/asterisk, /var/log, /var/run and voicemail etc on that one, possibly leaving the main card mounted read-only for most of the time.
Setting up
Using Digium cards for FXS/FXO
Zaptel modules
Use the command genzaptelconf -d to generate new config files. Generates /etc/zaptel.conf and /etc/asterisk/zapata-channels.conf files.
Echo cancellation and gain settings on FXO lines
This page covers both of these topics:http://www.asteriskdocs.org/modules/tinycontent/content/docbook/current/docs-html/x1695.html
This one is interesting too: http://www.rowetel.com/blog/?p=18
- Edit /etc/zaptel.conf to adjust receive and xmit gain levels.
- Use ztmonitor channel to see levels during a call.
- Use asterisk -r and the reload command to change settings during a call.
Web interface
Voicemail
User interface
On delete of message, move it to Trash/
Administration interface
- Should trashed messages be deleted or archived? How often?
- Should messages marked as old be deleted or archived? How often?
- Per user control of Trash/ ?
Service providers
Internet Telephony Service Providers
Links
Digital signal processing and Spandsp: http://www.soft-switch.org/
The Blackfin project http://rowetel.com/ucasterisk/
