unlocked iphone, when calling those on family plan displays calling voicemail?

[jarvxd]

just unlocked an iPhone and when ever I call those on my family plan my phone displays "voicemail" as the name. The call goes through to the right number dialed but always displays "voicemail". If I go to dial in the number it displays the correct name below the number but still displays "voicemail" when the call is placed even though the name was shown when dialed.

Any thoughts?

 

[jarvxd]

turns out my SIM card was too old to properly function with the new towers. All I did was get a new SIM when I got a cheapie phone when I switched family plans but I'm sure ATT would burn anyone a new one if they were running into similar problems and could come up with half a decent excuse.

Hope this might help someone in the future.