My job requires me to get text message alerts 24 hours a day telling me that there is a problem with our websites. There are 2 different companies and therefore at least 2 different sources of messages. They are text messages being sent from our server using either Twilio or originating as emails that hit the cellular provider and then come to my phone as a text message. I'm on iOS 9.2.1, iPhone 6.
I want all other alerts, phone calls, and text messages totally silenced automatically during Do Not Disturb hours that I set. For example 11 to 7.
So far I have not found a way to do this. I can allow calls from favorites, but there is no way to add these text-only contacts to my favorites. I just tried it again -- the add to favorites option is not there when I view them as contacts. It's there for regular contacts.
Therefore currently at night I plug in my phone to charge but I have to leave the mute button off and DND off and the ring volume up so that if and when a text comes in from the automated work system, it will make a noise and light up my lock screen and wake me up.
And of course now I'm getting other things like Whatsapp notifications from people at 12:30 a.m. because they assumed my phone was off or muted at that time, or whatever.
So how can I DND/mute everyone except these work text messages?