Deploying Asterisk-based VoIP Solution

VoIP helps enterprises in lowering the expenditure on travel and

communication between branch offices. Here, we show you how to deploy an Open

Source and free Asterisk IP PBX, and use it over VPN in a typical branch office.

There are different ways in which you can deploy the VoIP server. You can

deploy it at a branch or the head office or use a third party service provider

who will host it for you. But if you have multiple branches, it is best to have

the VoIP server at the head office. It will be easy to maintain and you don't

need any extra resource. But first deploy a VPN for a typical branch office

scenario. For implementing VPN you will need to have a VPN server at the head

office. This VPN server can be a physical server or it can be virtually hosted

in your data center. For deploying PPTP or SSL/TLS VPN visit http://pcquest.ciol.com/content/topstories/2009/109020106.asp,

where we show the detailed deployment of a VPN. Now let's deploy Asterisk.

For creating SIP extension, navigate to Add Extension page and then select generic SIP device from Device options and then click on Submit button.

Deploying Asterisk



Installing asterisk is pretty easy and the installation process is very much

similar to deploying a Linux distro. Just grab the latest Asterisk ISO from

www.asterisk.org, burn it and boot the machine with it. During the installation

process it will ask some basic questions such as password, location and within

minutes the installation will be over. After installation, the machine will

reboot and it will show you the IP and the port over which you can access its

web based management console. Now open a web browser from any computer which is

in the same subnet as that of Asterisk and type the IP address followed by the

port number through which you can access the management console.

The console automatically logs you in the guest user mode and to get things

started you need to login using administrator credentials. For this, click on

'switch' link on the top left corner. A dialog box appears where you need to

provide username as 'maint' and password as 'password.'

After you log into the administrative console of Asterisk, first create

extensions so that the user can make use of the Asterisk box. For creating

extensions, click on the PBX menu and then select PBX settings. Click on the

extensions option found on the left panel (under the basic category) and after

that click on the 'Add Extension' option found on right side. Choose device as

'Generic SIP device' and click on submit. After that specify the user extension

for example 101 or 102 and provide the display name. Display name will pop up in

the CID (caller identification) when the person dials an internal extension.

Next fill up the secret field which is similar to users password, and will be

required while logging into the Asterisk box. There are other input fields which

are optional and depend on the user requirement. For eg, recording as an option

on incoming or outgoing calls, voice mail passwords, email addresses, etc. Once

this is done click on submit button and the extension is created. Repeat these

steps to create as many user extensions as you want.

Asterisk is an open source and free IP-PBX which provides all the basic functionality of PBX including voicemail.	If you want to make a call to any mobile or landline phone, then you have to add out bound route rule, which can be found under basic settings.

Installing the client



Client tools are basically soft phones that will be used by users sitting at

a branch or head office. There are a number of soft phones which are freely

available on the Internet such as 3CX, XLite, SJPhone, etc for Windows and Linux

platforms. And all these work fine with Asterisk. For installing a soft phone on

the client system, download 3CX VoIP Phone (for Windows) from www.3cx.com. Once

downloaded, double click on the setup file and follow on-screen instructions to

complete the installation. Then go to file > connection, this will open up the

configuration window. Provide a profile name, your SIP account credentials such

as extension number, ID and password for connecting to Asterisk box. Next select

'I am in the office' radio button and specify the IP of the Asterisk server.

Then click on Ok and finally the soft phone is connected to the Asterisk server.

If the Asterisk server is hosted on a public IP then Choose 'I am out of office'

and provide the public IP in the field provided.

One box, different uses



You can use Asterisk box as a SIP server, i.e. call only the users who are

logged into the Asterisk server or you can deploy Asterisk as an Office PBX

system within your organization. Now let's see how you can use asterisk for

branch office communication.

A branch is connected to the head office over VPN, with the Asterisk server

deployed at the head office. Hence, clients sitting at branch offices can

connect to the Asterisk server using a soft phone and become online on Asterisk

server. Now for calling any user, you just need to dial a particular user's

extension using your soft phone. You can also avail the option of calling

someone on their mobile phone. For this you need to have an FXO card installed

on the Asterisk server. An FXO card helps in connecting normal phone line to the

Asterisk server.

In case you just want a SIP server then you can host Asterisk virtually,

which will save the cost of buying a new hardware for Asterisk. But if you also

need the functionality of calling someone's mobile phone then you require a

physical server, as FXO cards are not supported in the virtualized environment.

For more details in deploying Asterisk, visit http://pcquest.ciol.com/content/DIY/2007/

207062901. asp or for specific queries regarding Asterisk deployment, visit our

forum: forums.pcquest.com.