I have a lenovo 6000+ mobile, and there's one option of IP phone call, so i wand to know how to make IP phone call from my mobile?

That is called Wi-Fi calling on T-Mobile, and you just need an app that will allow you to make phone calls over Wi-Fi.

Your phone might automatically make IP calls when a Wi-Fi network is available.

I don't know how to make call using Wi-Fi, can you give me reference doc. Or something like so i can make IP Phone call