Can only assume its this type of scam. Doesn't explain why those of you with credit seem to have more credit after the call though???
Wangiri scam calls (wangiri is a Japanese term meaning something like “one ring and cut”) work by using software to ring random numbers, especially mobile phone numbers, and dropping the call after one ring.
The scammer hopes that the victim will notice the missed number and ring it back, not realizing that they’ll be calling a premium-rate number. Variations on this theme include calls that play a recorded message when the call is answered. While the message may implement a range of scams, one common gambit is to offer a prize, some kind of rebate, or some other incentive, to persuade the hopeful victim to call a premium rate number. Preferably an offshore number, since the illicit profit is likely to be greater.
Both myself and my wife got a call at 3am and 4:42am this morning. Not from this exact number, but same dialling code and area code etc. we're both on Vodafone.
My girlfriend got a call from this number she is on a O2 network but her number is an 087 last night. I then get a call at 5am this morning but the last two digits were slightly higher, 50 something. I am a Vodafone customer