The best way to understand is probably by asking your retailer. You can also do a little research over the internet. Also, to know which handsets have VoLTE, you can check www.grameenphone.com/volte
skitto's new SIM offers
• 3GB bonus with 7 days validity with skitto app registration • 100 SMS, 50MB data & 10 taka mobile balance • 1GB bonus with 7 days if you buy the SIM with a promo code