William Blair analyst Bhavan Suri views Avaya's bankruptcy filing as a "potential large opportunity" for RingCentral. The enterprise market is transitioning toward the adoption of cloud telephony solutions, and the bankruptcy of Avaya only further accelerates this, Suri tells investors in a research note. The analyst estimates the opportunity for cloud UCaaS players over the next three years from Avaya alone could be over $650M. He's confident in RingCentral's ability to garner a good portion of this opportunity given its "solid competitive position in the market." Suri keeps an Outperform rating on the shares.