Mitel Networks issued a terse press release on Wednesday, saying Richard Dell has left his position as president of Mitel U.S. effective immediately.”

Mitel did not respond right away to a request for more details surrounding Dells departure.

Paul Butcher, president and COO of Mitel Networks, is taking over as president of Mitel U.S. while the company looks for a replacement for Dell.

Mitel, based in Canada, makes IP and unified communications platforms and gear. Its U.S. headquarters are in Chandler, Ariz. The company has been losing market share to rivals such as Shortel, and said earlier this month its first fiscal quarter sales will come in lower than expected. Initial projections tagged revenue for the three months ended July 31 at between $163 million and $167 million. But then Mitel last week said it expects to report sales of around $160 million on Sept. 2.

Shares of Mitel closed 1.29 percent higher on Wednesday, at $7.04.