Vhreaking with VoXaLot

by J.R. Vela  (jrvela@aristasol.com)

Is phreaking dead?

In the days of war between the telephone companies and phreakers (phone hackers), many battles were fought.  Most hackers think about phreaking as the "good old days," when hackers just wanted to learn about the mysterious telephone system, while the telcos wanted to keep their secrets to themselves.

As we all know now, many secrets got out, which opened the telephone system to exploits such as the 2600 Hz tone used to gain access to telephone trunks.  Most of the old phone vulnerabilities have been plugged, or strong laws have been put in place to punish those who exploit these vulnerabilities.

Until recently, the telephone system had not changed much in the 100 years since its invention.  With the introduction of cell phones, the basic technology was about the same; the only difference was that telephony went wireless.

Today, cell phones do more than provide basic dial tone service; they have become true multipurpose devices.  The players in the cell business are still the old telcos for the most part.  Voice over IP (VoIP), on the other hand, has been maturing over the last few years.

Coupling VoIP with the growth of the Internet, a new telephony technology has the potential to explode in the coming years.  The traditional telcos feel that there is the potential for a disturbance which could impact the dark side of the force.

There are hundreds of VoIP companies, and the old telcos are not even in the game.  They are hanging on to the old network.  The new players offer telephony services with a technology completely different than Alexander Graham Bell's little invention.  VoIP offers an awesome playground for a new generation of phreakers.  VoIP phreaking, or vhreaking, is the new frontier.

In the old days, phreaking was driven by a desire to learn and be able to call friends for free or at low cost.  VoIP offers the same opportunities without having to break the law.  What follows is a description of how one can set up a free, or nearly free, telephone service to place calls around the globe.  First, let's review some common VoIP terms:

ATA:  Analog Telephone Adapter.  This is a hardware device that acts like an IP phone.  Unlike an IP phone, it does not have a handset and a dial pad; instead it has an RJ11 telephone jack where an old analog telephone can be connected.  An ATA allows you to use a traditional phone as an IP phone.

BYOD:  Bring Your Own Device.  This is a form of VoIP service where the provider allows you to bring your own device.  Some providers have devices that are locked to that provider's network.  You want a provider that offers BYOD connectivity.  The device must be unlocked for this to work.

Device Registration (Register):  When an IP device is configured to use a provider, the device will register to the provider's SIP server.  The device will look for the server and attempt to register with a user ID and a password.  As part of the registration, the device will send information about itself, such as its IP address, to the server.  Thus, when another user on the server calls this IP device using its SIP address, it knows which device to ring.  Some providers will allow multiple devices to register to a single account.  In this case, all the devices will ring at once when called.

DID:  Direct Inward Dial.  This is a telephone number in the PSTN that can be assigned to a telephone on a network.  You can think of the DID as your telephone number on the PSTN.

PBX:  Public Branch Exchange.  A mechanical switch that has telephone trunks coming in from the PSTN on one end and telephone stations on the other end.  It allows the stations to make and receive calls from the PSTN.

PSTN:  Public System Telephone Network.  This is the good old telephone network that phreakers used to enjoy.

PSTN Gateway:  This is a device that sits between a VoIP network and the PSTN.  It allows VoIP networks to communicate with the PSTN.

SIP:  Session Initiation Protocol.  This is an open Internet protocol used to establish communication between VoIP devices.  One of the advantages of SIP is that, unlike other VoIP protocols, it is open.  If you want, you can dig into the RFCs, but that is beyond the scope of this article.  For now, it is just important that you use a SIP VSP that allows BYOD.

SIP Client:  This is an endpoint device connecting to a SIP network.  It could be, among other things, a hardware IP telephone, a software IP telephone, an ATA, a PSTN gateway.

SIP Proxy:  This is a server that takes SIP requests and then forwards them to the right place for processing.  This is how clients come into the VSP's VoIP network.  SIP proxies face the Internet on one side, while connecting on the other side to a SIP server.

SIP Server:  Call processing equipment.  The SIP sever performs the functions of an old telephone switch or PBX.  The difference is that SIP devices work over IP and can connect via the Internet.  The SIP server holds a dial plan and is capable of routing calls between devices.

SIP Network:  The SIP server and all the SIP devices make up a SIP network.  You can usually call devices within the network by simply dialing the SIP number of the device.

VoIP Softpone (Softphone):  This is a software version of an IP phone.  You run this software on a PC, laptop, or hand-held device.  You will need a headset and microphone for the softphone to be useful.

VoIP Telephone or IP Phone:  This is a device that looks like a traditional telephone, but it is actually a computer.  It connects to a network using its Ethernet port.  It is used to make calls using a VoIP network.

VSP:  VoIP Service Provider.  A company or organization that provides VoIP services.  Most VSP are for-profit organizations trying to make money offering inexpensive telephone services.

I think we now have enough ingredients to cook up a nice home made VoIP system.  One of our goals is to build our telephony system keeping the cost as close to zero as possible.  Whenever possible, we will use free services.

First, we need to get an IP phone.  Since we are on a budget, we will get a free softphone.  We will use X-Lite as our softphone.  X-Lite is a free download from CounterPath (www.counterpath.com).  You will have to install X-Lite on your system and configure the audio levels for your headset and microphone.

The next thing we need is a free VoIP Service Provider (VSP).  There are many VSPs offering a variety of services.  A lot of them charge for their service; however, there are some that offer a basic service for free and an optional premium service for a fee.

For this exercise, we will use a free service from VoXaLot (www.voxalot.com).  We chose VoXaLot because it uses SIP and allows BYOD.  It is free, has free voice mail, is friendly with other SIP networks, has customizable dial plans, and allows us to use other VSPs to make and receive calls.  So, it acts like a hub.  This allows you to have a single SIP number for life!

When you register on the VoXaLot website, you will get your SIP number, which you can pick as long as it is not already taken, and password.  You will use this SIP number as your account number to register your IP phone and also to login to VoXaLot's web page to configure your system.

VoXaLot also has instructions on how to configure X-Lite.  There are four pieces of important information that you will need: your username, sometimes called your account, SIP number, or Authorization User; your password; the domain, voxalot.com; and the SIP proxy, us.voxalot.com.

Follow the instructions at www.voxalot.com/action/tutorial?itemOID=69

If all goes well, your softphone will register and it will wait for you to make a call.  VoXaLot has a special SIP number to do an echo test; just dial 600 to do your test.

The way we write down the SIP number is important because we want to give our SIP number to people we want to get calls from.

Let's assume that our number on VoXaLot is: 112600

Our SIP number will be: sip:112600@voxalot.com

This tells people that we are on VoXaLot's SIP network and our number there is 112600.  Other users on the same network can call us by just dialing 112600.

If your friends are on the VoXaLot network, then you are golden.

But since there are many VSPs, chances are that your friends are not on the same SIP network.

Peering to the rescue!

Many SIP VSPs have agreed to peer their networks.  This means that you can have calls that cross SIP networks.

SIP Broker (www.sipbroker.com) facilitates a large SIP peering network.

There are many networks that peer with SIP Broker around the world.  When a network peers with SIP Broker, they get assigned a "sip-code" to identify the network.

VoXaLot's sip-code is: 010

Another popular SIP network is Free World Dialup (FWD), which is hosted by pulver.com.

FWD's sip-code is 393.  So if we want to place a call from a VoXaLot IP phone to 861234@fwd.pulver.com, we dial: *393861234

Note that this form of dialing is unique to VoXaLot; other VSPs implement the access to SIP Broker with a different dial plan.

Peering allows us to call any SIP phone on any network that peers with SIP Broker.

Chances are that your friends using a SIP telephone service are peered up.  Some large VSPs, such as Vonage, do not peer with SIP Broker.  (Vonage used to do so, but for some reason they shut their gateway down.)

You can get a complete list of peer networks from www.sipbroker.com.  Note that with SIP networks and peering, the PSTN could be replaced as the main telephony network.  If we all had SIP phones on peered networks, we would not need the PSTN to talk to each other.  Obviously, we are not there yet.  The telcos don't want us to be there either.  The PSTN will be around for a while; we will have to deal with it.

Some of the peers on SIP Broker have PSTN gateways connected to their local telephone networks.

/his means that by calling a local PSTN number, anybody can place a call to a SIP phone on any network peered with SIP Broker.

You will need to find a local PSTN number by consulting www.sipbroker.com.

Call the number using an ordinary PSTN or cellular phone, and, when prompted for a number to connect to, dial: * + sip-code + number

For example, suppose you found that the number in NYC to call is +1-646-810-9280.  Call this number from a regular telephone or cell and, when prompted, dial *010112600.  You will get a call on your IP phone if the phone is currently registered.

Being able to get calls from the PSTN to the SIP Broker network is very nice.

SIP Broker makes this possible, but people are not used to this strange way of dialing.

A DID would be a nice thing to have.  DIDs cost about $6 per month.  There is one organization that gives free DIDs; however, they are in area codes in Seattle.

But they're free, so you can't complain.  Surf over to IPKall.com and sign up for a free DID.

When filling out the form for the DID configuration, use your VoXaLot number (112600) in the account field and specify the SIP proxy us.voxalot.com.

This will point the DID to your VoXaLot SIP phone.  It takes about an hour for the change to take effect.  Suppose you got a DID in the 360 area code and that the DID is 360-555-1004.  After the change takes effect, anybody calling 1-360-555-1004 will be directed to your IP softphone.  The IPKall DIDs are free, but expire if left unused for a month.

With this configuration, we can call other SIP IP phones that peer with SIP Broker.  We can get incoming calls via the local SIP Broker PSTN gateways or when callers dial our free DID number.  Not bad for freebies.  In the old days, this type of access would have made many happy phreakers.

With a small investment, we can upgrade our phone system to be able to make outbound calls to the PSTN.

Callcentric (www.callcentric.com) offers a pay-per-call service.

It works by prepaying an amount to credit to your account.  The minimum credit is $5; you can pay with PayPal.  Beware: the first time you do this, there will be an extra one-time setup charge of $2.03 and a $2.37 per month fee for emergency 911 cost recovery, so a total of $4.40 will be deducted from your credit.

This latter fee only applies to U.S. residents.  Callcentric claims that this is mandatory for phones in the U.S.

With VoIP, this is questionable, since you can have a U.S. DID while the actual phone is in another country.  There is also the question of softphones on laptops, which means they are mobile and so sending the registered street address for emergency will not help.

Okay, enough whining about 911 fees.  When requesting your DID from Callcentric, you get asked if the phone will be used outside of the U.S.; if so, you will not be charged the 911 fees.

Obviously, then, 911 calls will not work.  Once you have a credit on your account, you can call anywhere in the U.S. for about $0.019 per minute.

You can also make international calls.  The international call rates vary by country.  You can check the rates on www.callcentric.com.

Setting up an account on Callcentric is similar to the account we set up on VoXaLot.

You can call other Callcentric users, you can call SIP Broker with a nasty dial plan, and you can configure your X-Lite to register to Callcentric.  This is cool, but we don't need another SIP phone to manage.

Instead, we can configure VoXaLot to route outbound PSTN calls using our Callcentric account.

We can also configure Callcentric to forward all calls to our VoXaLot SIP number: 112600@us.voxalot.com

This way our IP phone will only register to VoXaLot and will make and receive calls through VoXaLot as well as Callcentric.  This entire configuration is done on the web pages for VoXaLot and Callcentric.

For the most part, it is fairly straightforward.  The only tricky part might be setting up Smart Call (also called Dial Plan) in VoXaLot, so that when you dial PSTN numbers, they get routed to Callcentric.

Read the VoXaLot Tutorials (www.voxalot.com/action/tutorialList).  I spent time playing with the Dial Plan to make it do cool things, like abbreviated dialing to my own area code and routing toll free calls through SIP Broker to avoid Callcentric charges.  I also route 900 calls to an invalid route, so I avoid calling these numbers with their premium fees.  The VoXaLot forum has a lot of discussion about dial plans.

Callcentric is just one of VSPs available.

There are others offer slightly different services and rates.

Pennytel (www.pennytel.com) offers low rates to many countries including the U.S.  They don't have the 911 issue and it works great with VoXaLot.

Using VoXALot to manage all your SIP needs, you can have multiple VSPs in the background.  The more VSPs you have, the more complex the dial plan gets, but you can benefit from lower rates and quality.  Beware that there are VSP's that are not fully SIP compliant or otherwise will not work with VoXaLot.

An example of this is JustVoip (www.justvoip.com).

Having to use the computer for telephony can be painful.  If your softphone is not registered, then you cannot make or receive calls.  An inexpensive solution is an ATA.  You can get an ATA such as the Grandstream HandyTone 486 for about $50.

It is well worth the investment to free up your computer and instead use an old familiar telephone set.  Another option is an IP phone, which are more expensive than ATAs but offer some extra features.  Some ATAs are locked to a particular VSP (such as Vonage), so make sure it is unlocked when you buy an ATA.

This would be a good time to activate your free VoXaLot voicemail.  Login to VoXaLot and navigate to the Voice Mail menu option.  Make sure that Voice Mail is active and select your PIN.  From your phone, access your voice mailbox by dialing 500.  Follow the prompts to record greetings and otherwise set up your mailbox.

VoXALot also allows us to create speed dials using the web page.  When you create a speed dial, you give it a number to identify it.  To call a speed dial simply prefix it with **; for example, **200 will dial the number configured in speed dial 200.

ENUM is a system that maps phone numbers in international notation (E.164 format) to URIs.

ENUM works with DNS records and it is in its early stages of development.  The idea is that you can register your E.164 phone number to have an ENUM entry in a global database.

For instance, our DID number has country code 1, area code 360, and telephone number is 5551004, so the E.164 number is: 13605551004

We register 13605551004 in the E.164 database and associate it with our SIP URI: sip:112600@us.voxalot.com

The idea is that VSPs could query the ENUM database before placing an outbound call.

Then, if the dialed number had a SIP URI, the VSP could route the call using the Internet, thus avoiding the PSTN.  Obviously, some powerful entities have an interest in ENUMs not becoming become popular.

VoXaLot is one of the few VSPs that queries ENUM records.  Every entry in their Smart Call Dial Plan has an ENUM option that can be configured.  This means that VoXaLot can check the number dialed to see if it has a URI; if so, it routes the call that way instead of going through the VSP which in turn routes out to the PSTN.

ENUM is a pretty clever idea.  The catch is that the owner of the number, you, would have to register the ENUM.

Do your friends a favor and register your number at www.e164.org.

Yes, you will have to create another account and fill some web forms to get the number registered.  They also validate your number by placing a call and reciting a PIN that you will have to type into the record before it becomes valid.  Hopefully, your friends have registered their numbers, so you can route your calls over the Internet and avoid PSTN charges.

Each VSP offers a number of features.

Some of these features are web-based.  For instance, Callcentric and Pennytel have a way to initiate a call from a web page.  This presents an interesting scenario.  You login to the web page, type the number you want to initiate the call from (this could be a landline or a cell phone), and type in the number you want to call.

When you click O.K., the first number will be called; when it's answered, the second number will be called.  I am sure you can see the possibilities here.

There are so many things that you can do with SIP networks.

A SIP-based telephony system is highly customizable.  You can do really cool things with it and have so much fun vhreaking.  SIP telephony is just becoming popular.  The number of SIP phone users is still small compared to the PSTN and cellular networks.

The number of vhreakers is also relatively small.  SIP telephony is probably in a state similar to how email was about 20 years ago.  The telcos are not very interested in having the VoIP technology explode.

Obviously, they do not want to lose customers and revenue.  That is probably one of the biggest reasons they have been against net neutrality.

They would like to impose a tax for ISPs (including VSPs) so they can get a piece of the action.

I hope this article has just enough information to spark your interest.

For a nice repository of VoIP information, visit VoIP-Info.org.