With regards to her lying, it is important to remember it doesn't have to be an all in type of situation. It seems like a common defense against her lying is how no troll would go through the effort of creating a fake escort website/twitter profile to manage for years on the off chance that Phil claims to have a GF he has to fly in from another part of the world just so they could pull the ultimate troll.
It's pretty clear that she's exactly who she says she is. That's been confirmed by multiple people at this point. I think we can also safely say that Phil paying for her services is true based on the way he acted during his stream. If she was just a troll trying to blackmail him with fake stuff, Phil would be talking about it nonstop. In fact, that would be the best early Christmas gift for him, because it would be a brand new detractor. Look at how much he loved to use SoK as an excuse. If this wasn't legitimate, he'd probably be going on and on about how mystery woman is the reason his Patreon is low/that he owes taxes/he has gout/anything else wrong with his life.
The core part of the story seems to be true. Phil has been hiring an escort and pretending they are his girlfriend. That's hilarious, and I can be happy with that. As for the specifics told by Kim? Those I would definitely take with a grain of salt. For what it's worth, I do think we're missing some background details. I think Phil said/did something which pissed Kim off. I could definitely see it being some sort of payment related thing, but I think there's a little more to it than Phil just not responding to a phone call. I could see Phil asking for additional services when she was there and agreeing to pay after the fact or something, and then not doing it. Or Phil trying to weasel out of payments. Maybe insisting she didn't hold up her end of the bargain in some area, so he doesn't want to pay for part of it, or trying to argue that because he bought her dinner or something they should deduct those costs. You know, usual dumb Phil stuff.
While the more intimate details would definitely be interesting and probably funny to hear about, it doesn't change the fact that the core story, Phil lying about having a gf/hiring an escort appears to be true. That's already hilarious enough on it's own, and it's likely bound to produce more hilarity when DSP inevitably has to bring it up again on stream. I'm sure he's already thinking up excuses to back out of that January reveal he promised, probably something about her being too camera shy, or if he's feeling extra manipulative, he might twist it around on his fans for not meeting a Patreon goal and urging them to donate more so maybe next month he can reveal her.