The caller ID reads "unknown caller" - not only the title of the fourth track from U2's new album but a sign that the Edge is on the phone.

"It's all go in Berlin," U2's guitarist says. He and the band are in Germany to play the ECHO Awards, the third in a string of performances that included the Grammy Awards and the BRITs.

The band is making the rounds to set up "No Line on the Horizon," its 12th studio album and its first in five years. And while the album represents a creative peak of sonic texture and musical detail, it's not nearly so ambitious as the two-year world tour of stadiums the band will launch June 30 in Barcelona. Billed as the U2360º tour, it will feature360-degree in-the-round staging that's never been seen before in venues of this size. (Further tour details will be announced March 9.)"We're very excited about the idea of going on the road with this album," the Edge says. "I think it's going to translate so well to the live context. The songs we've tried in rehearsal are sounding fantastic, so that's got everyone really fired up."

At a time when singles are emerging as the dominant way of consuming music, "No Line on the Horizon" is a fully realized album, one that could even revive the format, according to Interscope Geffen A&M chairman Jimmy Iovine‹or at least send the current incarnation into history with a bang. "We have to change the form of the album in order to satisfy the consumer and to get their attention on it again," says Iovine, who first worked withU2 decades ago. "I believe that's happening as we speak with this U2 record, and I believe this will be remembered as one of the last great albums in this form."

For "No Line on the Horizon," the band turned to producers Brian Eno, Daniel Lanois and Steve Lillywhite, who were also part of the songwriting process."We went to Fez in Morocco for two weeks to just work on music," the Edge says. "It was like a sort of musical composition workshop, and we all sat ina room together. Most of the ideas would have been generated there andthen."

Two songs on the album that came from that woodshedding emerged as two of the album's biggest: "Unknown Caller" and the epic "Moment of Surrender." "Those were songs that pretty much came together in the space of a couple of hours, and therefore probably were played in the final incarnation maybe once or twice," the Edge says. "The biggest difference this time I suppose was the starting out point for this record. We really didn't have a clear agenda as far as a release date or a particular feel for what this album would be.

"U2 doesn't have a formula for making albums, the Edge says. "We can go for awhile not really seeming to make much progress, then suddenly a song will really take a huge leap forward for one reason or another, particularly toward the end of the album. I use the analogy of the Tibetan monks who do the calligraphy; it's all about mixing the paints first, and that process takes a long time."