Thinking of switching mobile to Plusnet.
My current mobile contract (02) ends in a few weeks time.
The Plusnet offer looks good although some comments (on this forum) may suggest it's not brilliant 
I want to keep my existing phone number, and don't want to be phone-less in this process.
So what is the time line and business process to ensure a smooth transition and migration?
Let's say my current contract ends next Friday (or is that too late or too soon)?
Well I did it today 
Keeping my existing mobile number and now awaiting sim and transfer on day one
Well... keeping my old phone number, with a PAC and ordered Wednesday, chip/sim arrived on Thursday, left 02, Friday and joined Plusnet Mobile with old number on Friday and almost seamless transfer business process 🙂 
I wanted to turn off my voicemail messenger and found I couldn't do it remotely, so I had to report it and Plusnet said they would do it in two hours, and they did 🙂