j4 the main problem with analog was the ability to clone the numbers. Two signals are sent out when making a call, number your calling and your I.D. or number for billing. Radio Shack among others, sold a receiver to pick up your transmitting number. They then took phones and for about $50 would put the trapped number into it. Purchaser began their free calling.
Was costing sprint about $1 mil a month just in South Florida when I worked their. Thieves parked on highway bridges, or near them to get clean and numerous signals from people traveling.
Now if the purchaser of the stolen number got lucky, say a company who did not track their bills from their employees? Large real estate companies, etc. Sheeeet their are probably people still using stolen numbers from God knows when. Digital slowed down the stealing but now hackers are back at it. Check your phone bills, you could be next.
ADD: Radio Shack did not sell the receiver specifically for thieves to steal the numbers. But the receiver they were selling worked for the job.