cant add music from second computer

I remember a long time ago with my first (and only) iPod that I could only ever load music from one computer. Eventually, that changed but I have noticed recently that this restriction appears to be present with the iPhone. Maybe someone else with more knowledge can clarify but I'm thinking it's an Apple restriction that there's no way around outside a jailbreak.

 

You can only sync with one computer. Make a decision on which computer you want to use as your sync and then copy any missing music from the other machine on a USB drive to the sync computer.

 

Since pretty much forever Apple has had a hub/spoke model for iTunes & iDevices. You keep one central repository with iTunes and sync all your iDevices against its instance of iTunes. AFAIK they've never supported using an iDevice with multiple source iTunes instances.

In recent years they've included cloud services into that model such that an iDevice can get its content from Apple's online music and app stores and download directly. This allows someone to use iDevices without having to always sync content to the device from their computer, provided they bought the content from Apple.

I believe there are third party software programs which allow you to put music on a device without iTunes, but that may complicate things if/when you later sync the device to the iTunes computer if you've not replicated the content.

troutspinner is spot on - you really need to decide on which computer will be your central repository and use it exclusive of the other. With the ability to wifi-sync it's a bit less onerous when you have more than one computer.

 

Haven't done this for quite a while now but a couple of years ago I had two computers that I wanted to sync with my iPhone. I set up as normal one computer, then copied the Music folder (the folder with all music, movies, and, most importantly, the iTunes library files) and pasted (replaced) the one on the second computer. Essentially this "fooled" the iPhone into thinking it was syncing with the same machine, since the library was identical. Worked like a charm back in the day. Not sure if recent changes to iTunes changed this...

 

I don't have any links handy but people copy their iTunes library ID to other computers and are able to use both with their iOS device. If I wasn't in a hurry I'd give you a direct link. I'm not a "go search" guy but it is possible and you can search and find the information you need.

 

As you've already discovered, you can do what you want with an iPod, including the Touch, but when it comes to iPhones, it's a different story. I learned this with my first iPhone as well; 2 years ago with a new 4S.

I can't even guess why they treat the iPhone differently like this.