I searched for free services that allows to send free SMS using api but there are no such free services. They just allow free trial and then packages according to no. of messages you have to sent. There are some SMS gateway like Kannel that allow us to send SMS from our PC using a external model having a sim card.
I also installed BIM server by following Daman’s Blog. First, I got some errors because I gave the directory name “bimserver” where ever he stated <domain> in his tutorial than I changed it to my localhost IP 127.0.0.1 that solved my error.