Or you could just say you don't know?
Ugh, there's really no need for that! I actually worked in telecom for years, including integrating cellular network gear with third-party billing and settlement systems (like Amdocs.)
Billing is hugely complicated and the third party systems cost in the millions of dollars in licensing and maintenance fees. They include thousands of rules to deal with the variety of scenarios (especially in conflict-resolution) that play out when peers settle with each other. The peers themselves work out large and complex legal contracts before they're encoded into these systems.
Yes, this is why they negotiate this stuff before the fact. Switches see different things all the time, especially when there are bugs, outages, or misconfigurations.
The lawyers come in when there is actual conflict, e.g., when fraud is suspected, or anything outside the terms of what was already negotiated.
The value of a blockchain here is that these rules (the prenegotiated ones) can be executed by verifiable smart contracts, instead of trusting a third party like Amdocs. If there is a real conflict, there will still be lawyers involved, but with the added advantage of an immutable public (to the federation) log. The bonus (which is yet to be proven) is that costs will be driven down significantly without the middleman.
