I have discovered a very easy fix for anyone with the “The system could not validate login for unknown reasons.” issue while syncing outlook contacts to Samsung Instinct. .

1. Log in to sprint.com
2. Do you see your samsung instinct phone under your profile or does it show the old phone. If you are having the outlook sync problem, most likely your old phone is there under your profile.
3. Click on settings & passwords link on top
4. Click on update profile
5. Click on update phone
7. Enter your phone number, you will get a text message with code
8. Enter that code when asked on the website
9. Log out, log back in
10. Sprint Instinct should be there now. Click on “Online Tools” on top
11. Click on mobile sync to set it up.
12. Done, plug in your phone and sync away!

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