Understand Kannel

[angel eyez]

Hi 
I'm new to kannel and want to understand it. 
Can u tell me how the kannel is differ from other sms gateways. 
my another question is that i can buy the gsm modem and use it for sending and 
receiving messages what special feature kannel can provide. 
Also why bearerbox
and smsbox is started before sending any message. Why both services are used.




Any assistance will be really appreciated.
Regards
angel