On 2008-07-23, DevilsPGD <spam_narf_spam@crazyhat.net> wrote:
> In message <Iishk.15991$mh5.10641@nlpi067.nbdc.sbc.com> DTC
><DTC@no_spam_nothing_here.foob> wrote:
>
>>It still works for their ATT phones, but the manger upgraded
>>to an iPhone and the ATT VM no longer recognizes his number.
>>After you input the [cellphone number], is says its not a valid
>>number, but his iPhone can still call his VM.
>>
>>Any clues?
>
> Due to visual voicemail, the voicemail systems are independent. If you
> have another phone, you can swap SIMs to pry the numbers out.
>
> In short, what you need to do is pull the iPhone's SIM card, pop it into
> another GSM phone.
>
> Press and hold "1" until
> voicemail dials, then hang up, and check the recent calls.
>
> Most phones will reveal the number, although I did have one (Sony w810i?
> maybe, not sure which phone it was anymore) that just showed
> "voicemail", in that case, adding it to the address book revealed the
> number.

You could also look at the "Call Forward" or "Call Divert" setting.
The number it is forwarding to "If Unavailable" should be the voicemail
number.

Dennis Ferguson