The page is very dated, refers to old or unavailable plans, even defunct MVNOs.. but the main thing is the company has continued to keep the 0870 service running
PLEASE IGNORE THE CALL CHARGES, OVER THE YEARS THEY HAVE MOSTLY GONE UP BY A HUGE AMOUNT OR NO LONGER APPLY (Everyday 50 still inclusive off-peak).
Access Number: 0870 963 0011
Ideal maybe from fixed lines if not classed as a "known access number" so as FOC, old Orange contracts that that included 0870 & Everyday 50, Virgin Mobile 08xx tariff or if you have a very cheap/free way or service to call 0870
lastly that the number can be reached by the calling service/network.
http://www.abroadtel.co.uk/cheap_international_calls.php (See for destinations; India is included).