Hi. I don’t think this is handset related as it occurs on this phone and my previous z5 premium when I use my vodaphone sim. Certain friends mobile numbers are unable to call my vodaphone number. When they do they are told it’s unavailable or unknown. I contacted Vodaphone and they ran me through some setting adjustments that didn’t help and they sounded rather mystified . They were to get back to me but never did. I’ve also done a factory reset, which I didnt expect to help, as it happens on my previous phone too. Could a sim replacement help do you think? Would appreciate any assistance, thanks.