SIM900 AT command HTTP GET request not show the web page
From what I can see in your results, it seems AT+HTTPINIT returned an error. This means the HTTP service wasn't even successfully activated. So there's no way the commands you issued later would have been successful. From the AT command manual, AT+HTTPINIT is necessary before you can do any HTTP-related stuff.
You need to run the command AT+CGATT=1 to attach GPRS, even if your query shows its value is already 1. 
It could also be that your APN requires authentication, using a username and password. So once you find out the username and password authorized by 'indosatgprs' (customer care?), you can use them in the following commands.

    AT+SAPBR=3,1,"USER","Enter the username here"
    AT+SAPBR=3,1,"PWD","Enter password"


Both commands should return OK if successful. To view all the parameters you have set, you can use AT+SAPBR=4,1. If all the parameters are satisfactory, and you have sufficient airtime in the SIM, then you can attempt AT+HTTPINIT. Only if this command returns OK, should you proceed to run AT+HTTPPARA-related commands.