Lesson learned - cellular can be expensive


Just wanted to share my costly experience using the 3G Nova. I’ve been working on a project that need to provide network redundancy using a cellular modem device like the Nova. Late last night, I was testing some code I found on the Internet that somewhat accomplished the task I needed. I had a wired, wireless and the Nova connected on a Raspberry Pi 3 and was disconnecting each connection to test whether I could still access the Internet. When I started my test, my monthly Nova usage was about 9.5mb. My testing, using pinging and traceroute commands, went on for about an hour, after which I stopped the code, went to bed but forgot to ‘disconnect’ the Nova. In the morning, to my surprise, I had magically used about 66mb. I don’t believe my pinging tests could have used that much data and not sure what was happening all night but I wanted others to not make the same costly mistake. Based on this experience, I find using cellular service to be to costly for my project and I am forced to abandoned it.

Lesson learned - cellular can be expense $$$$



Sorry you had that experience.
This is an issue when people are developing on the Pi because the Pi tends to run services that use data in the background. We’re in the process of building out some improvements to our libraries that might help here by preventing the Pi from using cellular for its system functions in certain cases. Stay tuned.


Hey 5310,

While using cellular can be expensive there are definitely ways we can reduce the final cost.

Have you had a chance to optimize your use case with our available plans? For example, if you are planning on using less than 1mb/month the Developer Plan is the way to go. However, if you plan on spending more than that you are looking at $0.60/MB after the first MB when you could be paying only $0.40/MB on the Pay-as-you-go plan. Furthermore, if you know how much data you will be using our monthly plans offer even more attractive prices per MB.

Also, if you are planning on a large deployment we also offer custom plans to adjust our offerings to your specific use case.

Here at Hologram we believe that data cost alone should not be a reason to abandon a cool cellular project.



I’m sorry about my past post but it wasn’t anything negative toward Hologram. It was about letting others know that cellular usage is occurring even when you think nothing to going on and the service is disconnected. I was shocked at the amount of data used. And since this morning, with only the Nova plugged into the PI, my total monthly usage went from 75mb to 108mb. Is it using data even when it isn’t in ‘connected’ mode?

As for my project, the main focus was to have redundant internet connectivity to service a home security alarm. With cellular usage should only occurring when normal WiFi was not available. So in a ‘normal’ operating environment, my monthly usage would be minimal or zero. Right now it looks like it’s using ‘data’ whenever it’s plugged in.

I also like to thank the Hologram staff for their quick response and their willingness to offset some of my mistake. I did send a link to BenStr about the software called Conman that I was testing to see if I could get something that would provide the redundant solution. FYI, from what I’ve researched and tested ‘network bonding’ is only available between wired connections. No Wlan or PPP connectivity is provided. Anyone have another solution??



you should be able to determine what happened overnight by looking at your hologram logs in addition to any logs you may keep.


I have noticed similar behavior, and have gone so far as to set up local firewall rules to block all traffic outside of those sent directly to hologram.io. But, I suspect that the PPP overhead is being counted against usage even when no traffic is being generated, and possibly even network announcements leading to data “usage” as long as the modem is powered on even if it isn’t connected.

I really would like someone with Hologram to comment and give a detailed breakdown about what counts as traffic and what doesn’t. It would be nice to know how much data is consumed during the session setup, and then how much data is used per minute/hour/day to maintain the connection so that we can figure out if it makes more sense to open up the session and leave it running sending small amounts of data frequently (because the session maintenance cost is low but the setup cost is high), or maybe we would be better off queue up larger payloads and then opening a session just long enough to send them and disconnect (because the setup cost is low, but the maintenance is relatively high).

And if someone really wanted to have an honest discussion about why $.40-.60/MB is seen as reasonable for hobbyist/developers in an era where we typically pay $.01/MB or less for consumer data. I mean I understand that it makes sense for businesses that monetize their traffic, but for hobbyist is is kind of a smack to the face. I assume that Hologram is acting as a VAR, aggregating user traffic in order to buy data in bulk from the major carriers, so I would expect them to get a wholesale prices much closer to the consumer rate, and if that is the case is a $.49-.59/MB markup really justified by the small amount of traffic devs and hobbyist typically generate. If someone was just willing to give us a real idea about how all of this works then maybe these CompuServe era data rates wouldn’t seems so crazy.

Now, if you could get us down in the $.01-.10/MB rate the cell and ppp overhead creep wouldn’t be such an issue, but since the system isn’t transparent, and the logs don’t separate out overhead, it is kind of frustrating when you run a short test sending a few dozen < 100B messages over one or two days only to find you are somehow getting close to exceeding your 1M/month allotment. And trying to be frugal means shutting down your modem for the rest of the month in order to avoid unexpected overages and waiting for your counter to reset.


My experience with a RPi Zero W connected thru the Hologram Nova (wifi is config as an AP with hostapd, so no traffic going out on that) all the time running a LoRa single channel gateway is about $0.70 / day, +/- some, using latest Raspbian. The gateway phones home to The Things Network every 30 seconds.

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