So it appears that Airtel will take your money for a shiny new iPhone, but has absolutely zero support for it. God help you if you want to use a value-added service like (gasp) voicemail. I’ve been subscribed for a month and I only just got it working.

Here’s the thing: in Mumbai, the voicemail number is 555, except it isn’t, and most of Airtel doesn’t know this. After a number of complaints, a mysterious call from an Airtel employee told me to use 567 instead. This works. Still no idea how to set a custom greeting.

So you now know your voicemail number. Great! Except that your iPhone doesn’t. It still thinks it’s 555. You tell it otherwise by punching in a USSD code on your phone dialpad thus:

*5005*86*567# (press “call”)

Now your iPhone knows it’s own voicemail number. Brilliant. Almost.

Here’s the other thing: the iPhone doesn’t have settings for “call divert” like other phones. That is, there are no explicit settings for whether the call should go to voicemail if unanswered, busy or out of coverage. The iPhone manual is also vague about this. However, since voicemail is a network feature, it’s possible to set options using network USSD codes, and generic GSM ones at that! What I used:

Send to voicemail if unanswered: **61*567#

Send to voicemail if out of coverage: **62*567#

I didn’t use this one, but it’s useful because you can then send any call to voicemail by simply pressing the lock button twice (busy signal):

Send to voicemail if busy: **67*567#

There’s a whole bunch of options to these well, so I’ll just link to the sources:

http://www.iphonehacks.com/2007/09/voicemail-hack.html

http://www.theunwired.net/?item=how-to-diverting-voice-calls-by-using-ussd-codes