As a long time telecoms guy these comments are interesting and all are right to a degree.
POTS -plain old telephone service is disappearing but there is no replacement yet for emergency calls that is reliable yet nor easy ways to detect when a caller is 'engaged, or to charge accurately if that's required..
Radio is always unreliable for the reason mentioned plus these delivery mechanisms need line of site-no good in hilly terrain or where there are extensive woodlands or in big cities. Replicating
a nationwide wireline network is virtually impossible due to the scale
Telcos still own most of the local network and rent to ISPS and also own large long distance and international networks which they also rent to ISPs
Overall you get a sort of pyramid effect with the bottom-customer retail being impacted by ISPs but with the Telco having a product too-as you go up the network the big telcos dominate the ownership of whatever network facilities are used.
But they do face a challenge and more changes are to come-with VOIP do you still need a phone number or will your Facebook ID do the job instead.
An interesting time
PB