Hi
I am also using Reliance Fixed Wireless Phone LG LSP 350R for using internet. You can kill the electrical intrference by providing two capacitor of 1.0 MFD 500V in series between Line & Netural of your Electrical Inlet and center of the capicitor to Earth point. Remember Earth point connected with a Eirth Pid only and the potential difference between Netural and Earth should not more than 2.5 volts.
If posiable kindly send me (USB to Serial cable convertor -FTDI) and Reliance USB Connect Kit for Reliance Fixed Wireless Phone LG LSP 350R or send me link to download the same. My Email address is adeebraza@sancharnet.in
Thanks
Adeeb Raza