Voicemail notification and change voicemail number for iPhones

**5005*86*1<vm>#     Instruct the iPhone to call the number <vm> when the [Voicemail] button is pressed

(the iPhone screen flashes briefly to indicate the command is accepted)

*#5005*86#                Check the <vm> number that was used in the last **5005*86* command

(the iPhone shows a black screen, with the number <vm> in the middle)

##5005*86*                Clear the <vm> number to be used when the [Voicemail] button is pressed

(when checked with *#5005… the iPhone only briefly flashes)