by July 16, 2006 0 comments

This second in a series of articles on VoIP takes you through the process of
setting up your own VoIP solution such that you are able to make and receive
voice calls over IP. The basic steps involved in this are as follows:

  • Signing-up with a VoIP service provider (VSP)
  • Configuring the VoIP adapter to work with this VSP
  • Assigning it a PSTN DID (direct-inward-dialling) number to receive
    incoming calls
  • Configuring the broadband router

As discussed in the previous part, there are numerous options available when
it comes to selecting a VSP as well as the VoIP adapter. This article explains a
configuration using X-Lite (soft-phone) or Linksys (earlier Sipura) ATA hardware
as VoIP adapters, and uses InPhonex or SIPphone as a VSP, coupled with IPKall as
the provider of a (free) U.S. PSTN DID.

IT managers
Configure a Linksys adapter and sign up with a VSP to make free calls using VoIP

Start by signing up for a free account with a VSP. When you sign-up with
InPhonex or SIPphone, you will be assigned your unique account number — known
as a Virtual Number (VN). The VN serves as your login name (username) and forms
part of your SIP address (used for receiving incoming calls). InPhonex and
SIPphone (and most other VSPs) offer free outgoing calls within their network.
However, if you plan to make outgoing calls to PSTN phones, you will need to
purchase (using a credit card) “pay-as-you-go” (or prepaid) minutes.
The complete article is also provided in the current issue of PCQ forums. A
table providing sign-up details for both VSPs is given in it.

Configuring the VoIP adapter
Soft-Phone: Search the Internet to download the free X-Lite version 2.0 from
X-Ten. Download the software and follow instructions to install it on your
computer that has a broadband Internet access. In X-Lite, click on the
“Menu” icon to launch the configuration menu. 

The Sipura VoIP adapter has a net-based configuration page that can be used to quickly set it up

Hardware: Power on your VoIP adapter and connect a touch-tone
telephone to the “phone” socket. Next, using a network cable, connect
the VoIP adapter to your LAN and follow instructions in its setup guide to
set/identify its LAN IP. Using your browser, go to the welcome page of your VoIP
adapter using its IP address. Click on the “Admin Login” link and then
on the “Advanced” link in the upper right corner.

Next, you have to configure the settings for your adapter. General Settings
are non-essential settings, but help localise the reporting and logging time of
your hardware VoIP adapter. Network Connectivity Settings help the VoIP adapter
to work with your firewall — especially for correctly handling incoming calls
and routing them from the firewall to your VoIP adapter. Using SIP account
details, your VoIP adapter authenticates itself and connects to the VSP of your
choice. Your login credentials here allow your VSP to assigns your usage to your
account with them. Call Settings allow you to control the audio compression
settings — G711u uses least compression (more bandwidth) while G729 uses
optimal compression without loss in audio quality. The dial-plan settings define
how outgoing calls are to be handled depending, on the numbers that are dialed.
You can also define the Save & Reboot settings. For detailed tables for all
these types of settings, you can refer to the full article on the PCQuest Forum
( under
current issue.

Once the above configuration has been implemented, your device should be able
to successfully register with your VSP. A confirmation message to this effect
should be displayed on your VoIP adapter’s welcome screen. For those using a
hardware adapter, you should now be able to hear a US-style dial tone on lifting
the handset.

Making calls
First things first… dial one of the test numbers provided by your VSP to
verify connectivity (provided in the table below).

Test numbers to verify connectivity
  InPhonex SIPphone
Registration confirmation:
You will hear a recorded message confirming your connection with the VSP and repeating your VN
8400 17474745000
Echo: You will hear back, whatever you speak. This step helps confirm that your VoIP adapter and network is properly configured to handle 2-way audio (essential for a conversation 600 17474743246

You are now ready to make VoIP calls. While doing so, it is important to be
aware of where your VSP is — since that determines the prefix (access code)
you need to use. For example, you wanted to call the U.S. number +1 (360)
5554321. While using a U.S. based VSP, you would need to dial it as 13605154321,
however if you were using a U.K. based VSP the same number would need to be
dialled as 0013605154321. Similarly if you wanted to call a Singapore phone
number +65 96964321 — when using a U.S. based VSP you would need to dial
0016596964321, however with a U.K. based VSP the same number would need to be
dialled as 006596964321. The dial-plan setting above takes care of this (for
Linksys adapters), allowing you to dial ISD calls as you were used to. It is
always a good idea to refer to your VSP’s website for such calling

It is also important that you know the call rates. Call charges vary
depending on the calling plan that you have subscribed, the country you are
calling, the region therein and also whether the number is a landline, a mobile
or a toll-free number. Most VSPs publish the applicable call rates on their
website. Since the rates vary across VSPs, it is better to select your VSP
depending on the rates they offer to your calling destinations.

Receiving Calls
  InPhonex SIPphone
SIP Address @sip.inphonex.come.g.:
Free Account Incoming calls via VN (in-network) only Incoming calls via VN (in-network) and SIP address
Paid Account Incoming calls via VN and SIP address Incoming calls via VN and SIP address

To call other VoIP users, simply dial their VN or SIP address. Such VoIP
calls are usually free (since they don’t use a PSTN network), however check with
your VSP if they allow such calls. SIP addresses being alpha-numeric, can be
easily dialled using a soft-phone, but not as otherwise. Most VSPs also have an
online “control panel” to allow you to manage your VoIP account. Once
logged into your control panel, you can view account balance, call history etc.
and also set parameters for outgoing calls, call forwarding, credit limit,
recharge etc.

Receiving calls
Your VN can be used to receive calls from other users of the same VSP. Your SIP
address is your unique Internet identity (similar to an email address) and
allows you to receive VoIP calls from across the globe (subject to your VSP
allowing it). InPhonex and SIPphone both allow for incoming calls via your VN as
well as your SIP address (Table provided ablove).

Both these VSPs also provide a chargeable add-on service of a virtual PSTN
number (DID) that allows you to receive calls from PSTN callers. There are quite
a few other options (free and paid) to get PSTN DIDs for the country and region
of your choice. Such DIDs can be mapped to your SIP address. One such service
provider is that provides free Washington, U.S.A. area PSTN DIDs.
Similarly,  provides
free PSTN DIDs for U.K. Most VSPs do not charge users for incoming calls.

Depending on the VSP you choose, there are some details you will need to
sign-up for and configure your free DID from IPKall, the tabular details can be
viewed in the current issue of PCQ Forums.

Upon successful registration with IPKall, you will be assigned a PSTN DID,
which will forward all calls to your VoIP adapter.

Configuring your broadband router
In most cases the VoIP adapter would be operating from behind firewall and
router, and in all likelihood, would not have a dedicated live static IP. While
this setup works well for outgoing calls, it creates a unique set of problems
for incoming calls. To work around this, you need to (a) set your VoIP adapter
to have fixed IP address on your LAN, and (b) configure your router to forward
ports 5060-5070 to the fixed IP of your VoIP adapter.

Chirag Patel, CEO, Net4Nuts

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