Questions on PSTN Calling - PSTN breakouts map

Seems to me that the thinking is slightly confused, in that, as far as I know, there is no concept of a UK or US tenant. There is a tenant (although I do believe that it is possible to have more than one) and within that tenant there are users. The users are individually assigned a location as distinct from the tenant itself having a location per se.  The billing is then based upon that user's assigned location. So a user assigned a UK location but visiting the US and making a call to a US PSTN would use international minutes, but if while still visiting the US he calls a UK PSTN he would be using domestic minutes. I think the question of how the packets are actually routed is a quite separate question from what the billing algorithm does.  I think that at the moment the UK user visiting the US and calling a US PSTN would find that the packets go first to the UK and then back to the US but I am not absolutely certain about that. Obviously that is highly inefficient and not conducive to good call quality. I THINK that location based routing is intended to ensure that the traffic is not unnecessarily routed through the data centre in the users assigned location but would break out at the point closest to the Azure Network end point that they are accessing the network through and route appropriately. I am fairly sure that the Azure endpoint the user access the system through is assigned through a dynamic DNS. So, if your UK user is in the US, and the closest (in IP terms) Azure Network Endpoint is in New York his call would travel over the public internet to New York and then onto London within Azure rather than over the pubic network all the way to the Azure end point in London.  However, I could be wrong about the situation regarding the routing of the packets within Azure both now and also when subject to "location based routing" because I am not exactly certain what location based routing means. It is really a guess on my part - I hope an educated guess and the obviously highly inefficient routing of traffic unnecessarily across the Atlantic twice is part of what informs that guess as it is such an obvious thing that all parties would want to avoid.

I guess if you had a US user and they made a lot of calls to the UK PSTN you could assign that user who is physically in the US  a UK location and use UK domestic minutes but you are not supposed to do that because unlike consumer skype, skype for business is a 911 replacement service. I guess that if it was obvious that the user (or a lot of users) was in fact just a US user that had been improperly assigned a UK location Microsoft would at some point get upset about it and I am pretty sure it would be a breach of the terms of service.

I hope that is helpful.