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We're looking at adding an option to our product for Cat-M1 data connectivity. The data plans look interesting, but it's very unclear how the data is actually counted. For example... for these AT&T, Verizon, and T-Mobile plans with 1MB of data, does that include the TCP/IP packet overhead?

We have reasonably low data requirements (8 bytes/minute per sensor, 1-15 sensors per device... plus a 26 byte system data packet every 15 minutes). However, if TCP/IP overhead is included, then our 8 bytes/minute becomes a minimum of 88 bytes... possibly a LOT more if the modem is just barely communicating and gets a large number of retries.

Does anyone know how they meter this stuff?

We could drop down to just a data packet every 30 minutes or so, but we'd very much prefer per-minute data. If it includes TCP/IP overhead, then with one update a minute just the packet overhead itself is going to use a minimum of 3.5MB/month.

If TCP/IP overhead is included... Is there some system or protocol (M2X, MQTT, etc) that would be an alternative to straight TCP/IP where the network providers would count data differently somehow?

  • other question to ask is "how many bytes in 1MB?" 1,000,000 or 1,048,576? – jsotola Jul 12 '18 at 23:29
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    I am assuming 1000000. – darron Jul 13 '18 at 0:16
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    The only way you'll get a definative answer to this will be to ask one of the providers – hardillb Jul 13 '18 at 6:14
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    Well, I'm having trouble finding someone competent enough to answer this question. On top of that, I am not entirely sure I could trust an answer by some random support person on the phone. I'm hoping someone actually has experience with this. – darron Jul 13 '18 at 12:44
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You need to talk to the Biz to Biz team more specifically the machine to machine team. Here in canada the big three have specific teams that handle deployments like this so I would assume the same in the US. From what I remember the TCP/IP overhead doesn’t count towards your bandwidth allocation.

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  • This is close to a link-only answer. Do you remember from use, or old research? – Sean Houlihane Jul 24 '18 at 8:50
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    I spent 5 years as an account manager for Bell Canada on the handset side. I would cross paths with the m2m team quite frequently. – A.Stark Jul 24 '18 at 11:20

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