Why should non BSNL customers not have free access to 1-800 numbers in India?

It's very sad that Non BSNL users have to spend money on STD Calls to contact companies selling products or services, where as BSNL users can use the 1-800 number and get done for free.

Why this difference? Is it a form of churn prevention by BSNL? Is it a technical issue?

With 1-800 number the called party pays BSNL for 1-800 number unlike the other numbers where in calling party pays (CPP). Now with calling party and called party both within BSNL's network, total revenue earned is with BSNL.

Where as assume an Airtel customer calls 1-800 number, two providers are involved. In such a case Airtel needs to be paid for connecting the customer to the 1-800 number. Who will pay, should the calling party pay to Airtel? Or BSNL shares the revenue with Airtel?

In the interest of the consumers, companies should work towards expanding 1-800 numbers reach beyond BSNL's network. May be TRAI should expedite it’s ongoing work on Number portability (NPAC) so that consumers get the benefit of not just 1-800 numbers but can freely move from one provider to other while retaining the number.