Question: are we running out of phone numbers?
Answer: With ten digits, assuming a non-zero first digit, you can have 9,000,000,000 phone numbers. The population of the US (2012) is 313.9 million, or 313,900,000. ... [2] estimates that the US population will hit a billion in 2100, so a few years from then is probably when we will run out of phone numbers.