One of my customer is asking for setting up his own sms gateway, where his employees share sms freely. I suggested him to go with 1 of the bulk SMS API offered by other vendors. But he is willing to setup his own.
So when i went through different open source SMS gateways i found Kannel is best one. But it looks like we need to buy GSM SIM with some SMS package with GSM modem. By this every SMS sent will be chargable.
My questions is, how do way2sms, 160by2 works? I mean do they get charged by there vendor for free SMS sent by users? If no, Then how users are able to send free SMS?
Free sms is impossible with Kannel. Best way to deal with kannel is buying a sms-server service from a service provider. It will be very cheaper than normal connection fees. USB Modem will give you problems when try to send bulk sms.