[OKCon-Programme] SIP calls & OKCon

Wouter Tebbens wouter at freeknowledge.eu
Fri Mar 18 09:09:46 GMT 2011

Dear all,

as suggested at the last Programme Committee it would be preferred to 
use SIP for internet calls over Skype. Below follows an introductory 
explanation and some pointers.

We can use a conference room from the Free Knowledge Institute, which 
can be reached by using SIP calling to: 880 at voip.freeknowledge.eu
The system will ask for this password: 1234.

Please test it before so you'll be sure you can reach it for the next 

I hope it works out well for you! And be welcome at the telecom 
revolution ;-)



*Call using the internet SIP standard*

*Why not Skype?*
Skype is a non-free piece of software that uses a secret and proprietary 
protocol for making phone calls between its users. The phone network is 
therefore owned and controlled by one company.

*Why SIP?*
SIP (Session Initiation Protocol) is an open standard protocol for 
establish phone conversations over the internet, and can be compared to 
the SMTP protocol and is also defined by the IETF.

Thus a dynamic ecosystem of developers, users and phone companies is 
emerging that bases on this open standard protocol.


*How do I use SIP?*
Many developers have made available software applications that implement 
SIP. either published as Free Software or as non-free.

Several forms exist:
A. install a client similar to skype, set up an account and call for 
free between all other SIP users, from that account provider and others 
that use SIP.

B. like A but purchase some credit from a SIP enabled phone company that 
let's you call to plan old telephone numbers.

C. install (or rent) a server with a software PBX (cf. phone central). 
Asterisk is one of the most famous Free Software applications that does 
this for you. Once you have such server installed, you can create your 
own accounts, set up conference rooms and/or gateways to the plain old 
phone network.

D. buy a hardware phone that implements the SIP protocol and add your 
personal SIP account(s) into it and use it with A, B and/or C.

See for example:
Blink is a useful app: http://icanblink.com/ but you can find many others.

FreeCall is one of those companies that let's you purchase credit 
(mainly for calling mobiles) and (after buying initial credit) let you 
call for free to most landlines in the world.  http://FreeCall.com

The nice thing is to combine various forms. But maybe you want to start 
slowly ;-)


Wouter Tebbens
Free Knowledge Institute /Unlocking the knowledge society/ 
Free Technology Academy /Online education about Free Software/ 

More information about the OKCon-Programme mailing list