Quote:
Originally Posted by SpookyET
More on Visual Voicemail. I've been digging around. There seem to be 2 protocols by which the iPhone understands Visual Voicemail. One is ACDS, which is used by AT&T. It is SMS-based. It uses a SMS trigger to download new messages. It requires minimal configuration, just the APN and enable/disable toggle. It automatically downloads a configuration file from the server given by the APN.
The other method, which seems to be universally popular on all iPhone carriers, as well as non-iPhone VoIP carriers, is IMAP-based, the e-mail protocol. It doesn't use IMAP-IDLE to stay connected to VVM. It uses a GSM standard Message Waiting Indicator, which is used by traditional voicemail. It requires a lot of configuration entries, which cannot be edited via GUI. T-Mobile Germany use IMAP. I think 99% use IMAP.
It could look something like
MESSAGE SENT: VOICE=+12063130004@myemail.t-mobile.com (T-Mobile SMS Gateway Number)
MESSAGE RECEIVED: VOICE=+13105551234@myemail.t-mobile.com (Your phone number)
ACDS seems simpler. It might be superior since it doesn't come with a lot of IMAP baggage. IMAP was designed for complicated e-mail, not simple voice messages. On the other hand, one could easily implement a Google Voice clone over IMAP and not have to code something custom over ACDS. Many VoIP providers are capable of emailing you voicemails. But, like I have said, besides AT&T, I no one else is using ACDS. Everyone uses IMAP. It seems AT&T wanted a custom protocol.
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This would be an important step to making Google Voice seamless and invisible on the iPhone. SMS is already taken care of, thanx to Google's 406 prefix. I wonder if it would be possible to alter the phone app to prefix all dialed calls with your google voice number, and '2', as well.
Then, we could use the iPhone's inbuilt dialer, SMS, and VVM features, and be invisibly using our GV numbers, all without needing the GV Mobile app.
(Both GV Mobile, and voice.google.com/m require internet access to dial. It's kind of sketchy on EDGE, sometimes placing a call takes nearly a minute.)