Back in the day...
I seem to recall a general telco policy of retiring used phone numbers a minimum of six months, and much longer if there continued to be hits on the not in service number. I can recall a few exceptions when area codes/exchanges filled up, but for the most part, when you received a number from the phone company it was for all intents an unused number.
I don't know if it's abandonment of that policy, nearly free long distance, debt collection companies who buy up past due accounts or an upsurge in people skipping out, but I'm going nuts dealing with collection company calls.
I recently dropped Vonage as my primary landline service. Nothing wrong with Vonage, but the underlying broadband collection in this rural area is pretty flaky and I was tired of dealing with poor call quality. Previous locations with Vonage worked fine.
Decided to use my Google Voice number as my public number, but needed an underlying line from Qwest as cellular wouldn't meet my needs. My location is in a very rural area, one voice exchange, not a high growth area, area code was split a year or so ago.
The first number Qwest assigned started receiving one to two calls a day almost immediately. Mostly collection calls, but school truancy, school delay/cancellation robo calls, utilities and the occasional personal call. Despite the personal information involved, it was amazing the profile I was able to build up of the previous assignee. I know the full name (including kids names), home address, and a pretty good financial profile.
After about two weeks of this, I had enough, so I called Qwest and asked for a different number. They assigned a new number - same problem.
Citigroup, Barclays and an interesting group called MCM are particular favorites. MCM is apparently what's left of the old Fingerhut Catalog company. Remember them? They apparently fronted as a catalog sales company but made their money going after all the suckers who fell for their "easy terms".
My understanding is that informing these companies that they are not to call any more is all it takes to stop the calls by US law, even if I was the person they were looking for, much less a wrong number. But it's amazing how much they try to grill you when you tell them not to call. They want to know what number they called, how long the number has been reassigned and try asking the same questions in different ways.
Since Google Voice is the public number, changing the underlying physical number isn't a problem other than the hassle factor, but I'm amazed at what a issue this has been.