1 – The software to install
Unlike Skype, most Free and Open Source Software for VoIP can communicate with one another. You don't need to use the same software as your friend to be able to talk to him/her. What you need is a unique XMPP/SIP address and all software will be able to connect with yours. We will talk about XMPP/SIP in a jiffy, for now, let's instal the software. Pick the one that pleases you the most, it actually doesn't matter much which one you chose. I have selected just a few based on these criteria: must be free and open (of course), is functional and user-friendly (preferably) and being cross-platform is a plus.
- Jitsi is a neat software with many functionalities and it works on Linux, Mac and Windows.
- Ekiga is quite popular on GNU/Linux and provides free SIP addresses as well. It works on Windows too.
- Telephone is a minimal functionality application, for Mac users only.
- MicroSIP is a Windows only software that seems stable and simple.
- Linphone works on mobile platforms as well (Android, iPhone & Blackberry).
See an extensive comparison of VoIP software on Wikipedia here:
2 – Getting an XMPP (or SIP) address (free computer-to-computer calls)
Note: you can use either XMPP or SIP to do this but you cannot mix the protocols. In other words, you cannot call a SIP address from an XMPP account. XMPP seems better for computer to computer calls and chat (better presence notification) but SIP is necessary for computer to telephone calls.
An XMPP (eXtensible Messaging and Presence Protocol) or SIP (Session Initiation Protocol) address are similar to an e-mail address (email@example.com) and you can get one gratis on one of the sites below (there are many providers). It is similar to e-mail addresses in many ways but instead of text you will receive voice/video calls. As a comparison, it doesn't matter if you subscribe to Gmail or Hotmail, it doesn't matter if you use Thunderbird or Outlook, you will receive your messages because you have a unique address and everybody knows how to find you. It's exactly the same thing for XMPP or SIP. For computer to computer calls, get a free XMPP or SIP address with one of these providers. As a side note, XMPP seems to handle presence better than SIP (meaning that you can see if someone is online).
You can get an XMPP address directly into Jitsi as explained on page 1.
See a list here: https://xmpp.net/
There are many other providers. Type for example “free SIP address” or "free XMPP account" in a search engine to find them. If you are adventurous, you could also setup your own server and do without any third-party service.
3 – Buying credits to call land-line/mobile phones
To call land-line/mobiles you have to pay for the telephone call. The so called “VoIP” means that your voice will travel through the Internet up to the nearest location of the telephone you want to call, then, usually, a local call will connect you to your interlocutor. This is why VoIP is so cheap, the most expensive part of the call goes through the Internet. The price of the call will depend on the deal that a given VoIP company has with the local telephone companies and how much they are willing to charge you. In our situation, we want to subscribe to a company that can connect a SIP call to a telephone system.
One of the well-known companies in the Free and Open world is Diamondcard.us. They work closely with FOSS (including Ekiga and Twinkle) and part of their profit are donated to FOSS projects. They do not have a reputation of handling customer relations very well but they seem honest and competent. If you want to foster Free and Open Source Software, this is the way to go.
4 – Configuring your software and your accounts
Now that you have a software, an XMPP (or SIP) address and an account to call regular phones, we will configure it all. This is easy but can be confusing at times.
Your XMPP address is used to make computer-to-computer calls with other on-line users that, of course, also have an XMPP address. Your address will look like this: user-name@XMPP-domain. When you launch your application you will have to login providing your user name, your password and your XMPP domain (some software call it 'realm' instead of 'domain'). The password is the one you chose when creating your address. Once logged in you just have to type your friend's XMPP address to start a voice/video/chat conversation.
The service that you subscribe for regular phone calls will provide you with a SIP address. You should configure this second account on your software the same way you did with the previous one. From my experience with Diamondcard.us, the login and password to log into the site do not correspond to your user name and password to use the service. In other words, you should log into the site and there you will see your account ID number (=user name) and a PIN code (=password). The SIP domain will be sip.diamondcard.us. This account is used for outgoing calls to regular phones so, once it is configured you can call land-line phones using the address: country-code + phone-number@provider.
As an example, if you are calling a french number using diamondcard.us, the address to type will be firstname.lastname@example.org. (no leading zeros nor plus sign at the beginning)
To close this article, we will see on the next page how to enhance your experience and benefit from VoIP low prices using a regular telephone.