@weleasewoderick23
Incredibly rude. I would stop going tbh, or go - and if she does it, just say 'anyway, I best make tracks, I've got lots to do, and you seem busy anyway.'
I have a friend who is a decent friend going back many years, but every time I meet up for coffee with her (in the town that's at a halfway point between where we both live,) she always ALWAYS gets phone calls or whatsapp messages on her mobile phone. Sometimes 3 or 4 interruptions of 3 to 6 minutes at a time, in the time we spend together -which is often only about an hour an a quarter.
She has 3 daughters and one son - all adults in their 20s, 2 daughters have left home, but the son and daughter who remain, ALWAYS call her when I'm with her, asking where the teabags are, or if she can pick up some custard creams for them, or if she can pick up their prescription from the pharmacy. She chats for 4-5 minutes, OR they whatsapp her, and she sits there messaging back and forth for 5-6 minutes while I twiddle my thumbs. 
If it's not one of her adult DC, it's her mum asking if she can pick up some milk on the way to see her tomorrow, or her husband asking 'what's for tea?' It annoys me that she just HAS to answer them, and it annoys me that they message her or ring her when she is with me, and they knows she's with me.
In fact they all annoy me (her kids too,) for contacting her for trivial shit - or things that could wait an hour - when she's with me. It annoys me equally that she responds immediately to the messages, and doesn't put her phone on silent.
I asked her once (when she got calls and whatsapp messages from THREE people during our 70 minute coffee meeting,) if her husband and DD and mum knew she was with her friend - who she hadn't seen for 2 months - having a coffee. She said 'yeah they do. What are they like ha ha LOL.' 
It does smack a bit of 'look how incredibly popular I am and how busy my life is,' and it's enormously rude. I activate my 'do not disturb' function when I am with her, or anyone else, so we are not interrupted by anyone in my life. I get a few messages sometimes when I am with her, but never see them as I put DND on! Why can't she do this? 
She seems to love the interruptions, and she ALWAYS says 'anyway I am a bit busy today, better fly' (after 60-70 minutes or so!') Always got somewhere else to be, and someone else to meet.
It's so rude. I do like her, but this is putting me of seeing her tbh.