One result of the dicey relationship is the increasing search by the music industry for a future in which Apple is not so dominant. Many executives say they believe the future of music buying is over the mobile phone, not from buying individual songs but by paying a monthly subscription fee to hear vast database of music.

Image The iTunes home page, Apples soapbox for promotions.

But right now that is a tiny business in the United States. Forrester Research estimates that downloading music from Web stores like iTunes generated $1.5 billion in 2008, compared with just $70 million in wireless sales. Apple could win in this arena as well with its iPhone, but the music industry is looking to others, like Nokia, which offers its Comes With Music service, to become viable players.

“They’re still the biggest game in town,” said David Card, a digital music analyst at Forrester Research. “It’s really Apple and everyone else. I think the industry would rather have multiple outlets.”

Apple, according to a music industry official involved in the negotiations, offered to negotiate variable pricing about a year ago. Most songs cost 99 cents, of which the label receives about 70 cents and Apple receives the remainder, although the breakdown varies slightly among the labels.

Apple indicated it was willing to make the switch to variable pricing provided that the music companies  which negotiate individually with Apple to avoid colluding  would agree to license songs for wireless downloads on the iPhone, as well as drop copyright protections using digital rights management, or D.R.M., software.

All the labels agreed except Sony Music. Its chairman, Mr. Schmidt-Holtz, wanted the pricing to go into effect right after the announcement, while Mr. Jobs wanted a longer time horizon. According to a person briefed on the telephone call, Mr. Schmidt-Holtz and Mr. Jobs had a heated exchange by phone on Christmas Eve. Eventually, Sony gave in and agreed to a longer waiting period.

Even if Mr. Jobs does not get personally involved in future negotiations, music executives still fear dealing with Apple. One chit the company holds is the power of the iTunes home page, where it promotes music. They also say that the entire Apple staff, including Eddie Cue, the vice president in charge of iTunes who handles the relationships with the record labels, do their best to follow Mr. Jobs’s style in their own negotiating.