Units In Service—Year-end totals of combined one-way and two-way paging devices—were taken from USA Mobility's Quarterly Operating Results as found on their Investor Relations web site.
2004 was the first year that Arch and Metrocall reports were consolidated.
In the 2005 to 2006 time frame, I estimated that USA Mobility had a 58 to 60% share of the total US Subscriber Paging Market. My estimate for the end of 2009 is that USA Mobility's share is now closer to 50% since some of their subscriber erosion has been the result of churn to regional and local paging carriers, and not forever lost to cell phones. So continuing with this logic, my "best guess" is that the current total US Subscriber Paging Market is approximately 4.36 million Units In Service (UIS).
According to estimates that I hear from my paging friends, the US Private Paging Market is equal to or slightly greater than the Subscriber Paging Market.
So then my rough guess is that there are about 8 to 9 million paging devices currently in use in the USA. That includes both one-way and two-way paging devices. It does not include any wireless messaging functions that are incorporated into cellular telephones or wireless smart phones.
The difference between a "guess" and a consultant's more formal "estimate" is the amount of time spent in obtaining and analyzing the data. Since no one paid me for doing this report, I didn't spend a lot of time on the telephone interviewing carriers as I have done in previous years. This is my best guess. Your comments are welcome. Tracking the size of our industry should be a community effort.