Yes, I've asked the company. Officially, it's impossible.

July 21, 2009 2:56 AM

A question for IT and telecoms boffins: Help me understand voicemail. Specifically, what would need to go wrong with a mobile phone company's voicemail server for it to randomly connect customers to the mailboxes of complete strangers? Is it more likely to be an isolated technical glitch, a systemic network security problem, intentional foul play, or something else?
posted by embrangled to computers & internet (9 comments total)

Impossible to say. Sounds like something got corrupt. Have they taken it offline to check it, and can they see any problems?
posted by devnull at 3:20 AM on July 21

I don't know. I know on 9/11, my land-line voicemail got messages froma couple strangers. Did they misdial, or were the phone compnay circuits so overloaded that calls got misdirected? I don't know.
posted by orthogonality at 3:40 AM on July 21

My bet is that it will come down to something as simple as an intermittent hardware fault in a DTMF decoder chip somewhere in a switching trunk buffer. One time it hears 2125395555 as 1115395555 and the next as 3135295555, and the next time it hears it correctly. The DTMF decoder chip that is passed your passcode may be located in another stage or switching center of the system.

There's really not enough information to offer good troubleshooting here. A lot depends on the exact point in the switching sequence where the problem initiates. If the authentication stages are always passed perfectly, then the DTMF digits are always being handled properly, and the fault lies somewhere after that, on the voicemail server, perhaps with something as simple as a corrupted disk index, or sector tree.

Hard to say for sure, without exact details.
posted by paulsc at 4:11 AM on July 21 [1 favorite]

I worked for a company who provided Voicemail and related systems to 80% of the worlds Telco's

A few possibilities...
1) It's a technical bug, there are lots of them, you might just be unlucky.

2) It's an error made during provisioning. Your number may be assigned to multiple mailboxes, or another number may be assigned to yours. Internal factors may make it seem like it's random to you.

If it's 1, they probably know about it but they can't fix it until it's fixed upstream. 2, you might have some more luck with.

Call your provider, ask to be escalated to a higher level of support and ask them to "re-provision" your mailbox on their systems. i.e. a delete and recreate. Back up any messages you want to keep :)

Good luck!
posted by puddpunk at 4:20 AM on July 21

Thanks, paulsc. When the caller tries to check their voicemail, they hear a random selection of voicemail greetings, messages, and recorded system messages like 'message deleted'. Sometimes they play in part, sometimes in full. Then the system hangs up. This has happened to more than one customer, but it doesn't happen every time they call. That's about all the detail I have - does it shed any further light?

Just to be clear, this ain't my server. I'm just aware that the problem exists and that the company isn't taking action to fix it. Which makes me curious, and a bit surprised. I guess I'm trying to understand if, in the world of telecommunications, this kind of glitch is considered a Big Deal or just something pesky that happens all the time. How stable do mobile companies expect their voicemail servers to be?
posted by embrangled at 4:38 AM on July 21

"if, in the world of telecommunications, this kind of glitch is considered a Big Deal or just something pesky that happens all the time."

At a real, genuine telco? Big Deal. At a reseller operation, maybe not so much, depending on how fly-by-night it is. Taken as a whole, resellers tend to vary in description from "shady" to "possibly shady."
posted by majick at 6:35 AM on July 21

Voicemail systems are based on a database. It could be corruption in the database. If you are a frustrated customer, call the appropriate Utility Commission in your state. Find them through the Attorney General, whose office probably handles consumer affairs. What a horrible mess; people rely on voicemail being private. If they're that lax with voicemail, how lax are they with phone hackers?
posted by theora55 at 6:51 AM on July 21

embrangled, that definitely sounds like DTMF problems as the system uses them as an interface to control playing back the message etc...

Bad news is that DTMF problems can turn up in almost any place in the network. Good news is that this is a privacy issue and should be taken fairly seriously by your provider... You're right to make a noise about it :)

Where I worked, issues like this were fairly low-priority unless it was at least moderately widespread. Mostly because the issues were so hard to reproduce and track down.
posted by puddpunk at 11:21 PM on July 21

Thanks all, this is a great help. It's a real telco, and yeah, I see it as a privacy concern too. The company, not so much. Maddeningly, under local privacy legislation it's actually quite difficult to bring a complaint about someone else's privacy being infringed. Will explore other options.
posted by embrangled at 3:45 AM on July 22