VIVO Y55s mobile Network is 2100, Technology is GSM/HSPA/LTE. GRPS and EDGE also eneble in this phone. But normally you suffer for network speed and also phone have duel sim facility .2g, 3g, 4g LTE works with jio but network speed is too poor . Both sim are Micro sim type. Customer service is too poor, no response and if you have luck then you get touch with them but no immidiete action from them to proper service. If you choose VIVO Y55s mobile then you have to experient that type of situation. May be you have to wait for service there have not instant action. Charges and billing, yes in India it is charged but all operator has own call rates so its very cheap .Billing are as Normal tariff rate . So its not free its chargeble service at all but very cheap and billing also normal, different operator and their different tariff but its all normal billing scheme.