There’s only one circumstance where it could be rude, and that is when somebody is talking to another person, and the other person interrupts to answer their phone without apologizing first. But if you apologize first, then even this is ok.
Love Sam x
Oh yeah- of course. Although- I never know when my phone rings anyway due to the silent thing (and I don’t have vibrate on either) haha but yes- then I’d just apologise. But I’d do that in person anyway if I needed to grab someone passing by for a quick word (during my day job.)
If I’m not engaging with anyone else at the time though then I wouldn’t consider using a phone to be rude. Though my husband and I frequently ignore people to use our phones- though that’s just a mutual thing and if the other wants to say something then the phone gets put down. Just politeness! 
I must admit I get fed up when people I’m with have their noses in their phones instead of talking to me. But if I don’t know the people with their noses in their phones, it’s none of my business (unless they walk into me because they’re not looking where they’re going!) I could well have been provoked to be forthright with her if I were in your position!
What does upset me (although I admit it is none of my business) is parents who are constantly on their phones instead of talking/listening to their child/children. Seems to be the norm in our local playground…
That annoys me as well. Why have children if you’re going to ignore them.
No that’s not rude. Rude people check their phone while ‘talking’ to someone!