Hi Guys,
Was struggling with this for the past 2 weeks, and got it working finally.
I am using the Huwaei 4G LTE USB modem provided by Airtel, should also work for ZTE stick.
Here's what i did to get it to work.
1, Install the 4G connection Manager
2, Goto System Preferences - Network Connections
3, You will see a Huwaei or ZTE modem, Select that
4. In Configuration, Click on add new configuration and Name it "Airtel"
5. Leave, Telephone number, username and password blank
6. Click on Advanced at the bottom of the screen
7. Click Modem, Select "Generic" in vendor
8. Model as GPRS (GSM/3G)
9. APN as www.airtelgprs.com, left the CID in 1
10, Say OK in the screen and come back to Network dialog box
11. Click connect, it will get connected and you don't have to put in any proxies or any other settings.
12. Now you can un-install the Airtel connection manager and be done with it.