The Vertu Constellation cell phone seems sure to find a following among international travelers. Vertu (www.vertu.com), a British subsidiary of Nokia, has designed a device that tells the time in three locations simultaneously, incorporates a real-time currency converter and flight and weather trackers, and provides one-button access to 24-hour concierge service. The leather-backed phone is available in three metal treatments and five colors, at prices ranging from about $4,300 (for a stainless steel and alloy unit) to about $18,000 (for a phone in 18-karat yellow gold). . .