All users of Jabber based IM chat, Google Talk, MSN/Live Messenger or Yahoo! Messenger can use GTalk2VoIP service to initiate VoIP calls using CALLBACK technique. This means, our system can make VoIP call to your phone (mobile or landline), then make a call to your destination and merge two calls (legs). Callback is initiated by a single IM message sent to firstname.lastname@example.org.
Just talk to the robot! Use your instant messenger to say "CALLBACK +1-111-2223344 +1-555-6667788" to the email@example.com buddy. This will initiate a call to your phone number +1-111-2223344, then to your destination +1-555-6667788. It even works on your mobile phone if you use Fring or the mobile version of Gizmo Project.
The calls cost the normal GTalk2VoIP rates or the rates of your own SIP provider which you can also use at GTalk2VoIP. Each call leg is billed separately, so if both legs are phone numbers the final cost will "double". But normally it should be no problem to use your Fring to start a free call between your friends landline and the fixed line telephone next to you.
This seems much faster and easier than Jajah to me.