Question: rom March 2013 to October 2014, Omid Kordestani was the Non-executive Director at a company with headquarters in which city ?

full_context: Document 1: Vodafone Hungary: Vodafone Hungary, member of the Vodafone Group is a mobile telephone company in Hungary. It started to operate in 1999 after securing the third GSM 900/1800 MHz license of the country and it was the first provider operating in the DCS-1800 band in Hungary. Vodafone is the third largest mobile network operator of the country, and controlling 22,84% of the market as of June 2012.
Document 2: Amit Singhal: Amitabh Kumar "Amit" Singhal (born September 1968) is the former senior vice president of engineering at Uber, a position he took up in 2017, reporting to CEO Travis Kalanick. Prior to this, he was senior vice president and software engineer at Google Inc.. He was a Google Fellow, and was the head of Google's core ranking team. He left Google on 26 February 2016 as the Head of Google Search.
Document 3: Travis Kalanick: Travis Cordell Kalanick ( ; born August 6, 1976) is an American businessman.
Document 4: Khaled Bichara: Khaled Bichara (Arabic: خالد بشارة‎ ‎ , ] ) (born July, 1971) currently serves as the Chairman of Dada.it, and the Co Chief Executive Officer of Accelero Capital. Prior to joining Accelero Capital, Bichara was Chief Executive Officer of Orascom Telecom Media and Technology OTMT, Group President and Chief Operating Officer of VimpelCom Ltd. as well as Group Executive Chairman of Orascom Telecom Holding. Bichara played a pivotal role in the 6.6 billion merger of VimpelCom with Wind Telecom S.p.A, to create the worlds sixth telecommunications carrier. Before joining VimpelCom, Bichara was the Group Chief Executive Officer of OTH S.A.E. He sits on the board of OTH since 2003.
Document 5: Telenor: Telenor Group (; ] or ] ) is a Norwegian mostly government-owned multinational telecommunications company headquartered at Fornebu in Bærum, close to Oslo. It is one of the world's largest mobile telecommunications companies with operations in Scandinavia, Eastern Europe and Asia. It has extensive broadband and TV distribution operations in four Nordic countries, and a 10-year-old research and business line for Machine-to-Machine technology. Telenor owns networks in 13 countries, and has operations in 29 countries if their 33% ownership in VimpelCom Ltd is included.
Document 6: Vodafone: Vodafone Group plc is a British multinational telecommunications company, with headquarters in London. It predominantly operates services in the regions of Asia, Africa, Europe, and Oceania.
Document 7: George Conrades: George Conrades is chairman and former Chief Executive Officer of Akamai Technologies. Prior to Akamai, Conrades served as CEO of BBN Technologies. Before joining BBN he spent 31 years at IBM, running its U.S. and Asia-Pacific businesses and heading two manufacturing and development groups. In addition to Akamai, Mr. Conrades serves on the Board of Directors of Oracle Corporation, Ironwood Pharmaceuticals and Harley-Davidson.
Document 8: Anand Chandrasekaran: Anand Chandrasekaran is an Indian-born business executive who works for Facebook Inc. on developing partnerships and global strategies for Facebook Messenger. Previously, he was the Chief Product Officer of Snapdeal, one of India's pre-eminent Internet companies as well as Chief Product Officer of Bharti Airtel, the third largest mobile operator in the world.
Document 9: Vodafone Czech Republic: Vodafone Czech Republic a.s. is a Czech telecommunications company. It is among the largest Czech companies by revenue. It was established as Český Mobil (Czech Mobile) in 1999, when the government of Miloš Zeman granted it a free license to operate the third mobile GSM network. Its mobile network was called Oskar; the company itself was renamed in September 2004 to Oskar Mobil. In 2005 the international company Vodafone became the sole shareholder, which in November 2005, approved the most recent change in the company name. Czech Vodafone currently has over 3 million customers. The director is Balesh Sharma since the end of 2013.
Document 10: Robby Stein: Robby Stein is director of product at Yahoo. Previously he used to work for Google and was co-founder and CEO of Stamped, Marissa Mayer's first acquisition as CEO of Yahoo.
Document 11: Virgin Group: Virgin Group Ltd. is a British multinational corporation venture capital conglomerate founded by entrepreneurs Sir Richard Branson and Nik Powell.
Document 12: Vodafone New Zealand: Vodafone New Zealand is a telecommunications company operating in New Zealand; it is a subsidiary of the London-listed company Vodafone Plc. It is New Zealand's largest mobile phone operator, based in Auckland, and was formed in 1998, after Vodafone purchased BellSouth's New Zealand operations. The company employs over 3,000 people and has operations nationwide, with its main offices based in Auckland, Wellington and Christchurch. The company is part of New Zealand Telecommunications Forum.
Document 13: BT Group: BT Group plc (trading as BT) is a holding company which owns British Telecommunications plc, a British multinational telecommunications company with head offices in London, United Kingdom. It has operations in around 180 countries and is the largest provider of fixed-line, mobile and broadband services in the UK, and also provides subscription television and IT services.
Document 14: Optus: Singtel Optus Pty Limited is the second largest telecommunications company in Australia. It is a wholly owned subsidiary of SingTel (a company headquartered in Singapore) since 2001. The company primarily trades under the Optus brand, while maintaining several wholly owned subsidiary brands, such as Virgin Mobile Australia in the mobile telephony market, Uecomm in the network services market and Alphawest in the ICT services sector.
Document 15: Omid Kordestani: Omid R. Kordestani (Persian: امید کردستانی‎ ‎ , born 1963) is an Iranian-born American businessman who has been the Executive Chairman at Twitter since October 2015. He was previously a Senior Vice President, the Chief Business Officer, and a special advisor to the CEO and founders at Google during July 2014 to October 2015 and was Non-executive Director at Vodafone from March 2013 to October 2014. Kordestani had also previously been at Google from May 1999 to April 2009, reaching the position of Senior Vice President for Worldwide Sales and Field Operations.
ground_truth: London