Citi analyst Michael Rollins says he does not have a strong view on why shares of Vonage Holdings are down 6.6% in the last two days. After speaking with the company, the analyst believes Vonage not being included within Gartner's 2017 Unified Communications as a Service Magic Quadrant could explain the selloff. The removal could raise questions over Vonage's competitive position within the market for unified communications, Rollins tells investors in a research note. He finds it difficult to quantify the possible financial impact from the company's absence from the Quadrant, and admits he is surprised by the move. Nonetheless, Rollins says his firm remains a buyer of Vonage on the recent weakness. He keeps a Buy rating on the shares with a $9.75 price target.