Fig. A: Configuring your router’s firewall to enable VoIP
by letting through data packets for call setup, ringing,
» Dial Plan: (xxx|xxxx|xxxxx|xxxxxx|*3xxxx|*4xxxx
NOTE: Your device may not support this setting, which
defines valid keypad inputs for dialing.
Since you’re probably behind a firewall, you also
need to point it to a STUN server in order to direct
calls around it. (STUN is the handy acronym for
“Simple Traversal of UDP [User Datagram Protocol]
through NATs [Network Address Translators].”) With
a Sipura adapter, you do this by enabling STUN and
all of the VIA options except for Insert VIA rport. Use
the STUN server stun.fwdnet.net:3478 and disable
Send Resp to Src Port and STUN Test Enable.
All-soft alternative: If you don’t need a traditional
phone or RJ- 11 connectivity, you can set up free
VoIP with any SIP VoIP phone or even an Asterisk
switch. For a software-only version, download free
SJphone PC software from sjlabs.com/sjp.html and
talk on a headset. One version is preconfigured for
FWD, so you can go the easy route and skip Step 5.
6. Make some test calls.
First, dial 613 and see if you can hear the Asterisk
operator. Speak, and you should hear yourself a
fraction of a second later. The longer the delay, the
more latency on your connection and the more
echo your callers will hear. Ideally, you’ll hear
yourself almost immediately.
You can also check the time or your phone
number by dialing 612 and 958, respectively.
See “VoIP Phone Tricks” on the following page
for more calls you can make.
7. Call your new home number.
If it’s been at least an hour since you got your IPKall
Washington state number, dial it from your mobile
phone. Your VoIP line should ring. Now you can hand
that number out to your mom, or to people whom
you do not want using up your phone minutes, like
credit card companies or your utilities.
If your adapter cannot register, or you can make
calls but don’t hear anything, then you have a NAT
or firewall issue. Try reflashing your firewall’s firmware or reconfiguring. If you hear a ring, but then
hear a fast busy signal when the party answers,
you have a codec mismatch between adapters. You
might try uLaw protocol on your adapter, although
G711u is usually the most compatible. Advanced
users can try G729, which is a low bitrate codec.