Transferring test app to iphone

I usually get a few people with iphones to test my apps. I give them an ipa file that they can transfer to their phone using itunes (dragging ipa file onto their phone name in itunes).
Nearly all the time this works but i have noticed that for a couple of users, nothing transfers and there is no message on itunes or the phone.
Is there another easy way to transfer this file to their phone?

Thanks

Do you have those phone’s UDIDs set up in the Devices section of developer.apple.com?

Yes, i have their UDIDs set up.
I just noticed that the same file transfer works on my pc but not laptop.
Just wondering if there is an easy non-itunes way of doing this?

Thanks

Have you tried giving them the QR code which gets returned by VoltBuilder? It will work for about a day.

If you want to keep your apps on our server longer, here’s how.

I haven’t tried the QR code, but i figured out the iTunes drag file issue.

I used to drag my ipa file onto the phone section in iTunes to install the app on the phone.
Some of the different iTunes versions don’t support this which was my issue. The solution is to copy the ipa file then do a paste in the phone section in iTunes.