Re: Not office hours? No contact
@logicalextreme: don't add your work accounts to your phone
I'd also suggest reading your contract and your company's policies and "employee handbooks", etc. Chances are overwhelming, in my experience, that there are policies that prohibit putting company data - and that includes emails, messages, etc. - on non-approved personal devices. Effectively you are not allowed to add work accounts to your personal phone - the company can't expect you to break rules and policies, can it?
I realise there are customers and other calamities, and I do not hide my personal mobile number from colleagues. I tell them that I do not check work email or messages off hours or on weekends, but if there is a real emergency that can't wait till tomorrow of the beginning of the next week they can call. But I don't promise I'll be in front of a computer, so I may or may not be able to help.
This has never been abused. People don't think twice firing a message off, but when told they can use a personal phone number in an emergency they'll stop, hesitate, re-consider.