It says that only first 60 min are free with a SIP device

check this link: http://forum.voxalot.com/voxalot-support/2649-outgoing-call-via-voipraider-fails.html

It says that 90 days free calls are only valid with the PC software. If you use SIP device, only first 60 minutes are free and then, it will charge as normal rate, which is 0.015 euro per minute, I believe.

I'm asking here to confirm above info. If it were true, voipdiscoutn may be a better choice.