Broadband House Wiring


I'm a BSNL Broadband subscriber. I'm assuming that my home wiring setup is something like this:

The main phone line is split into two wires which go to different parts of the house (distant from each other)—one for the telephone and other for the modem. Now, without an ADSL splitter my internet disconnects when the telephone is used (expected).
                      +-------------> Modem
Main Phone Line+----->+
                      +-------------> Telephone
To rectify this, do I need to install ADSL splitters at both the phone and the modem or a single ADSL splitter where the main phone line is split? The second solution is obviously correct, but is the first solution possible as well? The first solution is easier as I don't know where the main line enters the house, and the BSNL technicians told me to contact an electrician as "it's not their job".
A single ADSL splitter would work for sure. I suppose you can try the option with installing two splitters as well but I don't think it would work.