Migration to UC, issues for vulnerable clients

It would appear that clients who do this over the phone are being asked to attend at their local Job centre for an identity check and to bring documents (there appears to be no set list) to check.
I have not seem this mentioned on this Forum - or have I missed it?

Not migration but a new UC claim due to new ill health causing claimant to stop work.
He has been ID'd over the phone, and though separate phone appts had been booked for Mr and Mrs, when the decent adviser realised Mrs was in the room, did hers too saving the second appointment. I can ask, if it's helpful to know , whether they had to photograph their Ids and send the pics.
I do know they had out of date passports accepted [same as they used for voting]