For setting up internet connection please refer to this post Configuring and setting up Huawei EchoLife EG8145V5 for bsnl ftth.
Open the browser and access http://192.168.18.1. user name is ‘Epadmin’ and password ‘adminEp’
Select advanced and select WAN, click on new
Select service type VoIP and enter vlan ID obtained from your service provider. choose DHCP for ip4 nad click on apply.
Choose advanced WAN > Voice> VoIP Basics. Here you should enter Outbound Proxy Server IP, Address of the Primary Proxy Server Ip and most probably these two are same for BSNL. Next Standby Outbound Proxy Server IP and Standby Proxy Server most probably these two are same for BSNL port number is 5060
For media port and signalling port choose the VOIP we created in First step.
Now click new button at Basic User Parameters (SIP) section. Provide your VoIP telephone number as registration user name. inthe format 91stdcodenumber for example for ArunachalPradesh it will look like 91360XXXYYYY here YYYY will be last four digit of your registered mobile number and XXX could be 295, 296, 297, 298 or 299. Normally VLAN Id will be 1831. For 299 series VLAN id will be 1849
Password is normally XXXYYYY part of your phone number.
selct the tickbox for Enable User: save and reboot.