# Technical question about UPS, Fedex, USPS package tracking **URL:** \ **Category:** Factual Questions\ **Created:** [April 1, 2022, 6:02pm UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119 "2022-04-01T18:02:29Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [April 1, 2022, 6:02pm UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/1 "2022-04-01T18:02:29Z")
Does anyone know about the internal workings of the system used for tracking for these package delivery services? Specifically, I’m wondering how the data gathered in the field by drivers gets to the shipper and customer. For fixed stations like post offices and sorting centers, which undoubtedly have direct connections thru the internet, that seems like a no-brainer. But when a delivery comes to a house in the country, the tracking number is scanned by a hand-held device and eventually gets reported to some central location. What is the mechanism of this data transmission? Is it by cellphone? Satellite? Is data sent one at a time, or in batches, and if in batches, are the batches made up after some time has elapsed? I suspect the handheld device doesn’t transmit to a fixed end-point, but to the truck, which relays data elsewhere. But I also don’t think the data is accumulated over hours, as I often get a notification of delivery by internet in less than a hour of actual delivery. I’m wondering what happens if the truck can’t communicate with the central location. Is the data just held until a connection can be made? Is one phone call made for each package? In my neighborhood or in the mountains, cell coverage is spotty, and it might be some time before a connection can be established as the truck goes around our many curves and hills. While I was writing this post, our USPS postperson came to my door with a package. I asked her this question, but she didn’t know the answer. Then I checked my inbox and found a delivery with a timestamp of 12:46PM. I had scribbled a note to myself that it was delivered at 12:48, and I imagine she entered the data before coming to my porch, and we talked for 30 seconds, so that means to me that the data was sent PDQ with no significant delay at all. At least this time. Any experts around that can elaborate on this technology? ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [April 1, 2022, 7:02pm UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/2 "2022-04-01T19:02:08Z")
[Googling](https://www.ccjdigital.com/business/article/14924038/ups-drivers-begin-using-new-handheld-computer), the device used by UPS drivers is called a DIAD, which uses cellular connections. ---
**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\ **Post date:** [April 1, 2022, 8:26pm UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/3 "2022-04-01T20:26:32Z")
Somewht related: my employer has a small fleet of service vans which are tracked in near realtime via Trimble. They recently had to have the tracking hardware upgraded because they used 3G cellular service which is being shut down. In the late 80s, UPS was working on a proprietary communication system. It raised a ruckus in the amateur radio world because the project took some our precious spectrum in the 220 MHz band. Their system never made it off the ground and, of course, hams don’t get our spectrum back. See History\>US Allocation. [1.25-meter band - Wikipedia](https://en.wikipedia.org/wiki/1.25-meter_band) ---
**Author:** ![Marvin\_the\_Martian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/marvin_the_martian/32/2898_2.png) [@Marvin\_the\_Martian](https://boards.straightdope.com/u/Marvin_the_Martian)\ **Post date:** [April 1, 2022, 10:47pm UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/4 "2022-04-01T22:47:43Z")
> [@Musicat](#): > > But I also don’t think the data is accumulated over hours, as I often get a notification of delivery by internet in less than a hour of actual delivery. Hell, I’ve gotten delivery notices fast enough to see the driver getting into the truck. So pretty much instant, at least in my fairly densely populated area. It’s really not that much data. My pool company has started sending me photos of the pool after they have serviced it - again they arrive almost instantly. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [April 2, 2022, 12:32am UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/5 "2022-04-02T00:32:03Z")
I don’t always get the data instantly. Sometimes there is a 30-45 minute lag between delivery and notification. I haven’t yet determined if this varies by which service (UPS, Fedex, USPS) is being used. **Dewey\_Finn** , thanks. I was hoping for a little more technical info than just a DIAD is in use. How often is the data transmitted from hand device to central location, and what happens if no cell tower can be contacted right away? Is the DIAD in continuous communication, regularly (like a call every 15 minutes) or sporadically? ---
**Author:** ![mixdenny](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mixdenny/32/2962_2.png) [@mixdenny](https://boards.straightdope.com/u/mixdenny)\ **Post date:** [April 2, 2022, 2:24am UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/6 "2022-04-02T02:24:32Z")
I had an expensive machine on order and I could track it on the Internet as the truck drove along. I even watched it make a loop somewhere! ---
**Author:** ![Kron](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kron/32/12444_2.png) [@Kron](https://boards.straightdope.com/u/Kron)\ **Post date:** [April 2, 2022, 3:17am UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/7 "2022-04-02T03:17:37Z")
I did a gig for UPS during the 2020 holidays; the DIAD I used was literally just a cell phone running a UPS app, so it was in nearly constant contact (as constant as is possible in rural Wyoming, anyway). > [@Musicat](#): > > I don’t always get the data instantly. Sometimes there is a 30-45 minute lag between delivery and notification. I haven’t yet determined if this varies by which service (UPS, Fedex, USPS) is being used. For the record, it is possible to forget to scan the parcel on drop-off, and only remember to do it at the next stop when you see that the previous address is still at the top of the list; the driver then has the ability to log it as delivered. The DIAD, though, also logs the location of the driver when a package is scanned out… both to ensure the driver is at the right place, as well as to help build a database of “correct” delivery locations. One of the major reasons I got that gig where I did was because I’d been a land surveyor in the area for many years so knew my way around, when your typical GPS application might send you to an area that is literally miles from the house you are supposed to be delivering to! ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [April 2, 2022, 4:11am UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/8 "2022-04-02T04:11:53Z")
You keep using the word “call” which is the wrong term to use when talking about cellular data. It’s not like some dial up modem where the cell phone has to make a call to establish contact with some data center on the other. Data can just go to cell towers whenever there’s a connection, and if there’s no connection undoubtledly the data is queued up and ready to go when it does establish a connection. It’s really not any different from checking e-mail on your smartphone. As the system is updated, it probably sends a small message like “package 19825812543 delivered 1103” and maybe the picture if the driver took one. It’s just a continuous trickle of data, same as any phone app you get or send regular updates from. ---
**Author:** ![md-2000](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@md-2000](https://boards.straightdope.com/u/md-2000)\ **Post date:** [April 2, 2022, 4:35am UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/9 "2022-04-02T04:35:01Z")
> [@SenorBeef](#): > > Data can just go to cell towers whenever there’s a connection, and if there’s no connection undoubtledly the data is queued up and ready to go when it does establish a connection. It’s an obvious issue, so presumably whoever wrote the DIAD-type app thought of it. Here’s how I would have constructed the app: Add the data to the queue - time, date, GPS location, parcel number, the method the deliver was registered - scan, manual entry, signature, etc… Make a web connection and try to upload the data. (analogous to “open the web page” then if it does, “fill in the web page form”) If there’s no connection keep the data in the queue. Wait for the “upload succeeded” response. If there’s no acknowledgement of the upload succeeding, keep the data in the queue. Every so often when there’s data in the queue - try the upload again. Have an option for manual upload by wifi (and if that fails, USB) when the delivery unit returns to local depot. Flag situations where duplicate data contains disagreeing information (i.e. scan location and manual entry location disagree…) The thing is, if you can think about a “what if…” situation, presumably so have the program designers. After all, half their business is assuring correct delivery and ensuring losses are minimized. Absolute worst case, I presume, is “the DIAD unit fried and never uploaded some data…” Presumably the result is a reconciliation when the truck returns - complete the list manually to the best of the driver’s ability? The server presumably can alert - “the following went out on Truck ABC and I have no resolution for them - delivery success or failure”? ---
**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\ **Post date:** [April 2, 2022, 11:53am UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/10 "2022-04-02T11:53:33Z")
> [@md-2000](#): > > Absolute worst case, I presume, is “the DIAD unit fried and never uploaded some data…” For tracking, perhaps that’s the worst, but for package survival, there are worse situations. This just happened on Monday. Check the guy nearly getting smoked at about 40s: [https://old.reddit.com/r/CatastrophicFailure/comments/tqfymn/40\_vehicle\_pileup\_on\_i81\_in\_schuylkill\_county\_pa/](https://old.reddit.com/r/CatastrophicFailure/comments/tqfymn/40_vehicle_pileup_on_i81_in_schuylkill_county_pa/) ---
**Author:** ![md-2000](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@md-2000](https://boards.straightdope.com/u/md-2000)\ **Post date:** [April 2, 2022, 5:25pm UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/11 "2022-04-02T17:25:15Z")
Of course, if road travel is a problem, you can use rail. One trains can carry a lot more parcels than quite a few trucks. > **['Like a Third World country': Gov. Newsom decries rail thefts amid push to...](https://www.latimes.com/california/story/2022-01-20/los-angeles-rail-theft-supply-chain-crunch-limited-security)** > > The crush of cargo at the ports of L.A. and Long Beach, plus limited security on rail lines, helped make cargo trains vulnerable to theft, expert say. ---
**Author:** ![DesertDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/desertdog/32/11503_2.png) [@DesertDog](https://boards.straightdope.com/u/DesertDog)\ **Post date:** [April 2, 2022, 6:56pm UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/12 "2022-04-02T18:56:33Z")
On the Virtual Railfan channel there have been a number of intermodal trains passing through Cajon Pass (Hesperia) with quite a few containers having open doors. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [April 2, 2022, 8:33pm UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/13 "2022-04-02T20:33:41Z")
> [@md-2000](#): > > One trains can carry a lot more parcels than quite a few trucks. UPS routes a _ **lot** _ of packages through a Chicago-area facility called CACH by rail. About 1.5 million per day, and that ramps up to about 3 million a day in December. Half of that is on rails - either in semi trailers or containers. And similar to the FedEx Worldport in Memphis, CACH also acts as a fulfillment center for some products. I order frozen Chicago-style pizzas now and then, and they originate at CACH. > [@mixdenny](#): > > I had an expensive machine on order and I could track it on the Internet as the truck drove along. I even watched it make a loop somewhere! The originator of that was Qualcomm, but now there are several competitors in the GPS tracking and monitoring world. Twenty years ago, the tracking was usually on the entire trailer, but now, something about the size of a stack of credit cards can be placed in an individual crate or attached to a machine. ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [April 2, 2022, 8:54pm UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/14 "2022-04-02T20:54:20Z")
Not everywhere has a cell connection. But it does has an address. I suspect data may be cached on the device and then uploaded when it gets a connection. Or back at the delivery facility. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [April 2, 2022, 8:59pm UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/15 "2022-04-02T20:59:34Z")
I doubt the driver would have to wait until they return to the depot to upload the data. Even if they’re in a spot with no cell service (and even that is going to be rare nowadays), surely they’ll get service further along the route. ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [April 2, 2022, 9:02pm UTC](https://boards.straightdope.com/t/technical-question-about-ups-fedex-usps-package-tracking/962119/16 "2022-04-02T21:02:28Z")
Yeah. That’s what I said.