You can copy Phone Book .vcf flies to your AT&T Cell Phone SGH-A157V then on your phone you can save it to your phone Address Book. This may also work with other types of files. I tested this with .vcf files on Windows 8.1, but I imagine it will work with other Windows versions.
1. Plug a USB cable into your PC and the other into your phone
2. Your phone will ask you if you are Charging Only or Media Transfer. Select Media Transfer
3, You will see SGH-A157V show up as a device on your PC file browser. Click on it and open it.
4. Open Other Files. This is where you can put .vcf files
Note: I would make a folder inside Other Files to put the .vcf flies, that way you can delete all of them more easily
5. Drag and drop your .vcf files into this directory. It will give you a warning. Just say yes (you can click yes to all)
6. Disconnect your phone from your computer. Now all your .vcf files are on your phone
7. On your phone. Select: Menu -> My Stuff (yellow folder icon) -> Other Files. You will see your .vcf files (or the folder you created)
8. Highlight a .vcf file -> Options -> Register To Address Book. This will copy the entire .vcs file to your address book.
Note: you can just use the center button on the phone and it will default to Register To Address Book. This is faster.
Note: .vcf files is what Microsoft Outlook 2010 uses. You can select a Contact and Save As to a disk file. You can also edit and create a .vcf file with Notepad. It is just a text file with a very simple format. Example: