Is your line now , and has it always been a single residential type line and never a ‘PBX’ type business line , like a 2 line group , for example (01234) 123456/1 and /2 ?
With multi line numbers , setting diversion becomes impractical, obviously a incoming call could be answered on line 1 or 2 , and depending on how the customer has their system set up , incoming calls could always ‘try’ line 1 first , and only if it’s busy try line 2 , others could share the traffic equally , so line 2 gets calls even if line 1 isn’t busy, so setting a diversion on incoming calls on a 2 or more line system would have to be a little convoluted by making the 1st line busy and then diverting the last line , so all incoming call would be diverted , for this reason (AFAIK) this type of call simple call divert is only really suitable for single lines , other products can do a similar job on PBX’s
I wondered if some historical ‘record’ for your number is prohibiting call diversion being available .
