yes, and multiple directory services are a great thing. However, when I dial +1.310.642.0351 it reaches the same number no matter where the call originates, in what phone network, who my LD carrier is, who my local telco is, or how many switches it passes through on the way.

Actually (and this is why I hate analogies), I have folks calling my home number, for someone else who previously was assigned that number, all the time. I've had that number over five years. We've had that discussion before, wrt rat-holing net-blocks. What if the netblock gets assigned to someone else? The other counter is that the number is the equivalent of the IP addr. You dial direct, you get the same phone. Use an older phonebook and you may have a different number. Two different phonebooks, yielding two different numbers, owned by the same person, is no problem either. Two different phonebooks, yielding two different numbers, owned by different persons, is probably a court case anyway. At the least, it's a trademark violation. It can all be drawn with a Karnaugh map.