Nonsense. Having the option to hear the details of the caller after hearing the message is standard in my experience of several other providers. The car analogy is useless. This is a really common feature of voicemail and BT aren't providing it.
And "Maybe it's just a mystery" means "I don't know", so why post?
Fusionmoth - you seem to be implying that I should somehow be embarrassed that someone called me and left me an important message but didn't leave her number or, equally, that I knew she was going to call and should have had her details. The fact is, stuff like this happens and the crappy voicemail service I get from BT can't deal with it properly. Hence my frustration.
Making dismissive, lazy assumptions about the situation is no substitute for properly investigating though (and if you're going to wade into a discussion in the way you just did, you should expect a response like that). For what it's worth (since you also haven't bothered to establish the facts adequately), the caller had previously contacted me through another medium, asked for my mobile number and promised she would call me. She had not given me her number. I had sent her my number earlier in the day and she called me as promised. I just happened to have no signal for about 15 minutes when she called.
The thing that I was most shocked about was that having listened to my voicemail message, I was not then able to automatically dial the caller. I'm pretty sure I've had this functionality on my voicemail with every mobile contract I've had since the late 1990s.
As for there being two separate networks, I could be wrong but I think you'll find that BT uses EE's 4G Network to provide its mobile telephony service. I am however aware that they are two separate products. EE, for instance, offers full visual voicemail for its customers using iPhones. BT does not. I accept that, but the plain fact is that if BT does not provide even basic voicemail functionality maybe it's not good enough for my needs and I need to move to a different network.
To borrow your BMW analogy, it's a more like BMW taking cars off the production line before they've had their brakes fitted and selling them as complete cars with a different branding.
I come to community forums like this to read valuable and informative discussions about solutions to problems I might be experiencing. I may not be a regular contributor to this forum but I have been to many other forums. If I have a problem and I need a solution I try to provide as much information as I can and if people make sensible suggestions I am genuinely grateful. If their suggestions do not work, I try to provide more information in the hope that others might find the information useful. If I don't have anything useful to contribute I try to avoid writing smug and useless responses.
Apologies to anyone on this thread that is bored by this discussion now. I will take my investigation elsewhere (or maybe just make life easier and find another mobile network provider)