The Internet Engineering Task Force is considering interactions between VoIP and the PSTN: Mass-Calling Events and autodialers figure prominently in a new Internet-Draft memo.
In the context of this draft, the PSTN is a legacy network. (_*NOW*_ how old do you feel? ;-) )
The IETF PCN Working Group has continued its work investigating pre- congestion and admission control mechanisms. This work has progressed under the current charter, but has not yet considered related legacy PSTN interactions or the need for ubiquitous connectivity between users on dissimilar networks. The PCN charter could be improved by a strong positive statement to the effect committing to future work addressing legacy networks.
In that light, please consider the questions below which include differential PCN treatment based on traffic types, security, and PSTN interoperability concerns. It seems helpful to have a touchstone of some concerns relative to the PSTN network and IP network Gateway in order to confirm that they will be addressed in future work. This attempt is motivated by a desire to avoid the accidental omission of a topic that may be hard to "retrofit" in later.