Cash-strapped Vodafone Idea on Friday announced a follow-on public offer of up to Rs 18,000 crore at a price band of Rs 10-11 per share, marking the biggest FPO in the country. The fundraise -- which comes close on the heels of a Rs 2,075-crore fund infusion by Aditya Birla group via a preferential share issue earlier this month, would give the ailing telco the firepower to improve its positioning in the Indian telecom market, where it currently trails larger rivals such as Reliance Jio and Bharti Airtel, by a wide margin.