In Skype there is an 'echo call testing service'.
I want to check a set of POTS telephones and telephone microphone headsets.
Of course, I can call a friend and ask "how does this sound?" for all the permutations and combinations - but, having used the convenient Skype service, this question is whether a similar land-line POTS call-testing service exists for dialed phone numbers?
Q: Does a POTS "echo" call testing service even exist?