What is responsible for phantom usage? (a 36-hour test)

Question

There is a ghost in my iPhone 4S/5.0.1 that is mysteriously ramping up the usage and consuming cellular data when the phone is dormant (sitting on table, no apps running, no user interaction of any kind). I've just completed an 36 hour test monitoring the charge state ot the battery. Throughout the test, the iPhone was a few feet from an active WiFi acaccess point (Airport Express), and several blocks from a GSM cell tower.  Every few hours, I clicked the Home button, noted the usage and cellular data consumption, and put it back to sleep.
Friday 11pm. The iPhone had been in its dock all evening, and the battery was fully charged. Usage, as reported by Settings/General/Usage was 0 minutes. Cellular data = 5.0 MB sent, 33.1 MB received.
Sat 11 am. Battery at 93%. Usage = 11 minutes. Data 5.0/33.2
Sat 2pm. Battery at 89%
Sat 5pm. Battery at 87%. Usage = 24 minutes.
Sat 11pm. Battery at 82%. Usage = 31 minutes. Data 5.1/33.5.
Sun 8am. Battery at 77%. Usage = 39 minutes.
Sun 11am. Battery at 75%. Usage = 42 minutes. Data 5.1/33.5
As you can see, the battery discharged 25% over the 36 hour test. From this, one can extrapolate that the standby time would be 144 hours (6 days), significantly less than Apple's claimed standby of (up to) 200 hours. However, I had WiFi and Bluetooth on. Apple's 200 hour claim is no doubt a best-case measure obtained with everything other than the cellular radio active. 
More troubling is the usage that was reported: 42 minutes over the 36 hour test.  The iPhone was completely dormant (sleeping) throughout the test, except for the 6 times that I poked it to read the battery meter and the usage stats. The screen was on for perhaps 15 seconds each time. From an end-user perspective, I used it for about 1.5 minutes, not 42 minutes.  Perhaps the iOS usage measurement rounds up to the nearest minute each time (just like cellphone carriers measure phone calls), in which case, I was (arguably) responsible for 6 minutes worth of 'usage'. 
My question: who or what is responsible for the rest of the 42 minutes of usage reported by iOS? I'd like to know what processes account for the reported 42 minutes. Who or what triggered them, and why are they counted as part of my "usage"?
I know what was not responsible. I don't have iCloud activated. There is no Mail being pushed, or Mail being fetched. I don't have an Exchange account. WiFi Sync is off. Location Services is turned on, but none of my apps that employ Location Services were active (Maps, Google, Camera+, etc). Knowing that they're power hogs, I have disabled most of the System Services that use Location Services (Diagnostics & Usage, iAds, Setting Time Zone and Traffic are all off). Cell Network Search is on, but the iPhone wasn't moving, had a nice strong GSM signal, and had no need to be searching for different cell towers.
If my six  'meter reading' events do account for 6 minutes of usage, that leaves 42-6=36 minutes unaccounted for. Perhaps it's a coincidence, but the test ran over 36 hours. I wonder if some system-level process is triggered once an hour or so, and gets counted by the iOS usage meter.
The other anomaly that my test revealed is the celluar data that was sent/received. It's very small, and certainly won't kill my data plan. But I have to wonder why any cellular data was flowing. The iPhone had a solid WiFi connection throughout. If iOS had need to send or receive some data in the background, why did it use the (expensive) cellular data channel instead of the (free) WiFi channel?

Answer 1

Page 22 of this document will give you some numbers that will allow you to estimate the total data used for a meeting. Keep in mind these numbers are what Adobe saw as average consumption, yours may be higher or lower.
http://www.adobe.com/content/dam/Adobe/en/products/adobeconnect/pdfs/web-conferencing/Adob e-Connect-9-Technical-Guide.pdf