Utilize the input text as a context reference, choose the right relationship between Bharti Airtel and Vodafone from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

But in cases of firms like Aircel, for instance, it can trade most of its liberalized 2300MHz spectrum with Vodafone or Idea – trading with Bharti Airtel could run up against the caps which prohibit a telco from owning more than 50% of the spectrum in any band or 25% across all bands.

Answer: owned_by