Update your phonebook to the new number format in seconds.
From October 27th 2013, phone numbers of some states of Brazil will have an extra 9th digit, these are the area code affected:
* São Paulo (11,12,13,14,15,16,17,18 e 19)
* Rio de Janeiro (21,22,24)
* Espirito Santo (27,28)
* Amapá (96)
* Amazonas (92 e 97)
* Maranhão (98 e 99)
* Pará (91, 93 e 94)
* Roraima (95)

The new number must have the format 9XXXX-XXXX

This app will scan contact list to find out which contacts needs to be updated.

Only cell phone numbers and from those states must be considered.

You can roll back the changes any time you want.