The date for the phone switchover will be the 30th May. Therefore any booked phone interviews upto that date should be fine to go ahead as planned.
I intend to try to get everything sorted our end on the evening of the 30th if all goes to plan but will provide updates around the time.
Please don't arrange any phone interviews for the 30th May at the studios. 31st might not be a great idea either just in case there are unforeseen issues.
The studios should be fine to otherwise use as normal on those days (so long as I can pop in and check the phone works when I'm done!)