How many telco fixed network voice lines will still be in use by about 2018? Not too many, industry associations and the Federal Communications Commission tend to suggest. Some have in the past forecast as few as 20 million total residential voice lines sold by telcos by about 2018.
That does not necessarily mean only 20 million lines will be in service, but that the number sold by former telcos could well be that low.
It is easier to note that “peak voice” happened around 2000, and that lines have been falling ever since.