AT&T, T-Mobile, O2 and most other providers delete messages from voicemail after a period of 30 days.
Some providers offer an extension of this period for a fee. Contact your provider for more information.
Voicemail
How long will iPhone voicemail messages remain in my voicemail box?
By Chad Shmukler - Published April 1st 2008 - 19:16 in Voicemail
Will voicemail work on my unlocked iPhone?
By Chad Shmukler - Published September 12th 2007 - 15:12 in iPhone Unlocking
• Voicemail
As you either already knew or have quickly discovered, the iPhone's visual voicemail feature only works on approved networks. Though a feature created and supported by the iPhone, visual voicemail is actually a service provided by your wireless carrier.
Does this mean your voicemail icon/button on your iPhone will be "broken" if you're using an unlocked iPhone? Thankfully, no.
