How do you change a contact?

1. Open your device's Contacts app .
2. Tap the contact you want to edit.
3. Tap Edit . If asked, choose the account.
4. Enter the contact's name, email, and phone number. ...
5. To change the photo for a contact, tap the photo, then choose an option.
6. Tap Save.

under contacts, bring up number then there should be a edit at top next to number name, press and change number, remember to save after you are done

Press phone/menu/settings. Is the speed dial for your voicemail showing correct in there? If so, and you are still reaching the wrong number, contact sprint and explain to them what's happening. It's possible your default vmail number has gone a little screwy in the number change.
the place to check your speed dial is phone/menu/speed dial.

Change your number
Block calls
screen calls
contact attourney

contact your provider. they could have towers down or have the wrong phone number listed. If you recently had your number changed then you need to have your phone reprogrammed. A lot of times it takes a manual reprogram to solve the problem.

-check the message center number then correct if it is wrong,the message center number can get of what sim card you are using,if you don't know the message center number contact the costumer service then ask for this.
-and also check the character support then change it to "REDUCE SUPPORT".

Contact service provider to obtain correct number and they should be able to walk you thru how to change the number to the correct number.

THe problem will be on your computer in your Outlook Contacts, look there for the problem, once you change it there re sync.

You need to contact your system admin...