Confirmation of successful application by phone?

I recently read the following in a FB discussion group.

Application submitted 8th Feb 2021
Bio on 1st Mar
Received phone call from H.O (private no.) today 26 Jul informing me, app is successful. I asked case worker regarding confirmation email/letter, he said they used to send emails however backlog or some other issues(line wasnt very clear) they had stopped doing so. He told me i would receive a letter in next week or so with instructions to book and attend a ceremony.

OP followed up later with the following, in response to warnings about possible scammers.

Thanks for looking out! When he called me, he addressed me by my government name and the type of application ive submitted, also the type of passport i had. He also informed me i had over payed and would receive a refund in the coming weeks. He didnt ask for any personal info/ payment details etc. So i thought it was safe to assume it was a genuine call. Time will tell i guess.

I find this suspect. Scammers, or genuine?

Considering how difficult it is to speak to anyone relevant over the phone from UKVI or Home Office (Case workers or anyone that can let you know where your file is at) I find it really hard to believe they would actually call you.

I've never had to call them but I've read stories from other people trying so many different numbers (some paid by the minute) and finding nothing but walls.

I highly doubt this is legitimate, unless they were in touch with the case worker via phone previously? Not sure.

There are occasional reports that UKVI called so it's difficult to tell whether these were within process or just chance, someone picking up the phone. Maybe "over-payment" is a clue, though these days online the system will tell you how much to pay.

Sounds Very Suspicious to me, I would never believe HO would call anyone to announce their results. They got a Postal address and email id to communicate for whatever reason. Must been call center scamming ppl.