Phone Dialing "+1" before some numbers

[sunrise913]

I also had the problem on my Samsung S7...but it was only for numbers of people who subscribe to "WhatsApp". (It appears as a listing on the contact detail page under the "View More".) I uninstalled my "WhatsApp" app and the +1 dialing listing was GONE. Re-installed WhatsApp and the +1 calling did NOT reappear. Hope this helps.

Sorry about the WhatsApp solution, it was wrong. While it did eliminate the +1 from the contact listing, it still added it back when dialing. Solution from T Mobile tech for my Verizon Samsung S7 phone:
Tap Phone Icon
Menu (three dots, upper right corner)
Settings
Scroll down and tap on "More Settings"
Scroll down to "Assisted Settings"
Tap and next to "Manual", turn it off (swipe to the left)

 

[Dwc330]

Fixed on sprint note 9.

I kept getting my phone to add 011 to all outgoing call regardless of where the contact was saved or how it was saved.

Problem fixed.

1. Go to your phone screen where you dial the number.).
2. Hit 3 dots on top right of screen
3. Go to settings
4. Go to more settings.
5. Go to us dialing
6. Turn it on!

Problem solved!

All of my contacts, replay to callers and app dialing is working great.

Hope it helps.

 

[ABRAHAM ARKOH]

Not sure if this help but looked to see if the smart dial was checked and when i unchecked it took the 1 off

Solution
This problem also happened when I bought Samsung s8 plus. I did factory reset initially thinking it will stop but it didn't. The only best solution I got was after I updated the phone's software version. The system update solved the problem.
Make sure you manually update the version of the phone, after that, rescan to check for another update. The new update will specifically notify you for an improvements to your Samsung galaxy s8+.
Steps
Accept it and download. After the update,
go to call setting from the calls log > other call settings > assisted dialing, uncheck the manual setting or edit to your country information.
You can also go straight to assisted dialing, 'search from settings' check or uncheck the manual tap.

Note that, when your system is not updated the assisted dialing will be automatically checked and hidden.