What is VoIP? VoIP is voice over IP and which the voice is carried over internet from source to the destination phone. What kind of investment one needs to start? A rental server and install freepbx system(as the name suggest it is free and it will accept calls from buyers to you). GSM gateway(china made 8channels will cost about 200 to 250USD) Local Sim cards. Internet Find the buyer. What kind of profit we can expect? It depends on country that you will be operating. E.g Sri Lanka, I believe local call rate is just about 2 to 3cents USD but outside we can sell at least double the cost. For a channel, we can normally run about 500minutes daily, even with 1cent US profit, it is 5bucks a day x 8channels=40USD daily.