NEW YORK (Reuters) - Cloud communications company Twilio has appointed a partner at Sachem Head Capital Management to its board, it said on Monday, as it faces pressure from several activist investment firms to make significant changes.

Twilio added Andy Stafman and expanded the size of the board by one person to 10 people.

The change removes the chance of a boardroom challenge from Sachem Head in 2024 when three Twilio directors, including Chief Executive Khozema Shipchandler and board Chairman Jeff Epstein, are scheduled to stand for election.

Sachem Head, which has been invested on and off in Twilio over the last years, built its current position in the last weeks, people familiar with the matter said. The exact size of Sachem Head's stake in Twilio could not be determined.

Twilio, which was founded in 2008 and became a publicly traded company in 2015, makes products that help developers build communication features for receiving phone calls and text messages. It has a market value of $11 billion.

The company has come under pressure from activist investors including Legion Partners and Anson Funds. Both have been pushing the company to explore strategic alternatives, including divesting the data and applications business or selling the whole company.