Missing voicemail messages after O2 sim swap from iPhone 4 to 5

[Anonymous]

I've just been given an iPhone 5 and so swapped sims with my iPhone 4 and transferred all the data using iTunes back-up. Unfortunately only about 10 recent voicemail messages have transferred, whereas those on my iPhone 4 (all still there) go back to 2012, just before my husband became seriously ill. I then tried to restore them via iCloud backup, with exactly the same results. What can I do to retrieve them? If v/m messages can't be transferred, why isn't there a warning? Needless to say I've rung O2, the carrier, today, with no success. All suggestions gratefully received.

[MI5]

It's possible they are stored on the sim but I'm not an iPhone expert so Ill flag it for @Anonymous who is an iPhone user to assist.

[Anonymous]

Thanks very much MI5.

[Anonymous]

Hi there

As far as I can see you turn on iCloud, is the phone with the voicemails backed up to the computer? & wifi then do a restore to your new iPhone via iCloud

[Anonymous]

Do you have visual voicemail

[jonsie]

You did a full back up to to iTunes? Anything stored on the sim should be saved to the phone before backing up. 

[MI5]

I've Googled this a bit and found that voice messages are not backed up anywhere, but they are stored on the networks servers.
An article on the Apple forum suggests this:
" Just go into visual voicemail and in the message list just scroll down to the bottom of the list. You should see a button labeled as "deleted messages", tap the button and a list messages will show. "

[MI5]

The same process mentioned here http://www.engadget.com/2011/09/16/iphone-101-recovering-deleted-voicemails/

[Anonymous]

Thank you. Unfortunately I think this refers to retrieving deleted voicemails, whereas mine were never deleted. They just vanished when I swapped phones. Curiously my text messages remain intact, as do my contacts.

[Anonymous]

@Anonymous that is because they were backed up to iTunes