Some Nokia's have a timed profile feature where by you can turn it to silent then it goes noisy at a certain time.
Although why any pilot in this day and age would give ops there personal number and not have "work" only phone I don't know.
You can get dual up to quad sim card phones these days as well if you don't want to be carrying more than one phone. Then when your off duty turn the offending sim to off line on days off.
I use a 35 euro dual sim Nokia 110. Nothing fancy but does the trick.