VoIPowering Your Office with Asterisk: Free Long Distance with Free World Dialup

This service gives you cost-free connectivity with tens of thousands of users around the world.

By Carla Schroder | Posted Dec 11, 2006
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In previous installments of our series on AstLinux, we learned how to install it on single-board computers, separate the root filesystem from the data files for easy maintenance and longer Compact Flash life, and perform basic administration chores such as setting passwords, network settings, and managing services. Today we'll get an account with Free World Dialup and configure AstLinux to use it. With a Free World Dialup account you'll be able to talk for free to all of FWD's customers, and all the networks that FWD peers with.

You won't be able to call people on the old-fashioned telephone network because FWD does not yet provide PSTN termination. However, with AstLinux you can mix and match commercial services as you like, and add other providers to take advantage of different service offerings and pricing.

FWD supports both SIP phones and Asterisk servers. For users who don't want to run an Asterisk server, but just connect a SIP phone, they offer voicemail, callerID, instant messaging, and status (presence) indicators, so you know if the people you want to call are online. They support calling toll-free numbers and have a white pages directory that you can opt into.

Note that FWD does not provide 911 service, so you're on your own there.

Asterisk users get to connect via an IAX trunk (and remember, cool people pronounce it "eeks"; lamers say the individual letters). IAX (Inter-Asterisk Exchange) is bandwidth-efficient, and since it uses only a single UDP port getting it through NAT firewalls is easy. You don't lose SIP, either, because SIP calls are carried over IAX trunks. Several calls can be carried on the same IAX trunk, which reduces IP (Internet Protocol) overhead. So FWD's support of IAX is a very nice thing.

Opening a FWD account
First haul yourself over to Free World Dialup and click the big green "Get Started" button to sign up for an account. Sometimes it take a day or two to get your account information. Registration is pretty simple, but there are some gotchas. After you are signed up, click the "Extra Features" link in your account to activate IAX. Keep hitting the "Submit" button until it says "Congratulations, your changes have been successful." For any changes you make in your profile, look for a confirmation before moving on.

Once you get your welcome email with your login and password, log in and change your password because email is not secure.

These instructions are different from the howto on FWD's Asterisk help page, because their howto is for a single user. Follow me, Grasshopper, and you shall have a nice multi-user setup.

Now fire up AstLinux. You'll be editing four files: /etc/asterisk/iax.conf, /etc/asterisk/sip.conf, /etc/asterisk/voicemail.conf, and /etc/asterisk/extensions.conf. (Yes, I know that last week I told you to edit files in /mnt/kd. The files in /etc/asterisk are symlinked to /mnt/kd, so either one works.) Copy and paste these examples exactly, except you must substitute your own FWD number, login, and password, and use your own username and extension numbers. In these examples the FWD login is linuxgrrl, password 12345, FWD phone number 567891, and the local AstLinux login is carla.

;;;;;;;;;;;;;;
;iax.conf
[general]

context=default
port=4569
bindaddr=0.0.0.0
disallow=all
allow=gsm
allow=ulaw
allow=alaw

register => 567891:12345@iax2.fwdnet.net

[iaxfwd]
 type=user
 context=fromiaxfwd
 auth=rsa
 inkeys=freeworlddialup

;;;;;;;;;;;;;;
;extensions.conf

[general]
autofallthrough=yes
clearglobalvars=yes

[globals]
CONSOLE=Console/dsp

;free world dialup settings
FWDNUMBER=567891
FWDCIDNAME=linuxgrrl
FWDPASSWORD=12345
FWDRINGS=SIP/carla

[default]
include => fromiaxfwd

[outbound]
;outgoing FWD
exten => _393.,1,SetCallerId,${FWDCIDNAME}
exten => _393.,2,Dial(IAX2/${FWDNUMBER}:${FWDPASSWORD}@iax2.fwdnet.net/${EXTEN:3},60,r)
exten => _393.,3,Congestion

[fromiaxfwd]
;incoming Free World Dialup
exten => ${FWDNUMBER},1,Dial,${FWDRINGS}

[local-users]
include => outbound
include => default

;our beloved AstLinux users
exten => 250,1,Dial(SIP/carla,10,rt)
exten => 250,2,VoiceMail(250@local-vm-users,u)

;extension to retrieve voicemail
exten => 500,1,VoiceMailMain(@local-vm-users)

;;;;;;;;;;;;;;
;sip.conf

[general]
context=default
port=5060
bindaddr=0.0.0.0
disallow=all
allow=gsm
allow=ulaw
allow=alaw

[carla]
type=friend
username=carla
secret=4545
host=dynamic
context=local-users

;;;;;;;;;;;;;;
;voicemail.conf

[general]
format=wav49
skipms=3000
maxsilence=10
silencethreshold=128
maxlogins=3

[local-vm-users]
;mailbox number, password, username
250 => 1234,Carla Schroder
Save all your changes, then reload AstLinux:
astlinux*CLI> reload

Firewall settings
If you are behind an iptables NAT firewall, you'll need to add a line to allow incoming UDP 4569:

iptables -A INPUT -p udp --dport 4569 -j ACCEPT

Testing your setup
Reload your firewall rules, then fire up an IP phone and dial the FWD echo test, 393613. Figure 1 shows how it looks on the Twinkle soft phone.

figure-1-twinklefwd.png

Then go to your your FWD account profile (my.FWD) and click the "Callme" button. The FWD server will call you and invite you to join a non-existent conference. Now you know your set up is correct and working.

You should also have your Asterisk console running with a verbosity of at least 3, so you can see what's happening as you test your FWD setup.

Next week we'll learn some troubleshooting tips, how to add more users to your AstLinux PBX, and how to add a second commercial VoIP provider to your system that include PSTN termination.

Resources
VoIPowering Your Office with Asterisk: Connecting AstLinux to the Outside World
VoIPowering Your Office with Asterisk: Installing AstLinux on Soekris 4801
VoIPowering Your Office with Asterisk: Running AstLinux From the LiveCD
VoIPowering Your Office with Asterisk: Introducing AstLinux, "The Professional's PBX"

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