Source of this statement?
I work for a medium size U.S. FCC licensed switched voice (part of the PSTN = public switched telephone network) and data provider. About a month ago, we started to see an increase in both switched voice and data traffic.
The increase, however, has not overloaded our network, but we have seen a small number of call incomplete conditions (i.e., a fast busy or a "your call can't be completed" message). Even in normal times, there are still a tiny number of incomplete call conditions (minor outages in a national network happen with so many carriers), but that number has only increased slightly.
We, like all carriers, are continuously rerouting traffic depending on load and routing rules in our switches. When there is a dip in data traffic, most users can't perceive the very slight delay unless they are streaming. On voice calls, you do hear the call breakup or the call can't be completed.
From our prospective, we see is a material uptick in traffic, but so far, it has not caused any significant outages on our network.