New to setting up and using IoT simcards and cellular modems - recommendations? - Page 1
Forum section: electronics / beginners

author: timbopoise
author_rank: Newbie
timestamp: June 08, 2023, 09:34:36 pm
content: Hi and thanks for reading and offering your input...I've been working on developing an ESP32 based SBC with a cellular modem, i.e. using PCBArtists' ESP32 LTE 4G Gateway product.I've been able to piece together the necessary code to connect over cellular using PPP and leveraging both "data" mode for IP comm and"command" mode for issuing AT commands, e.g. for sending SMS text messages.I'm still struggling to get the rest of the functionality working (i.e. sending SMS, receiving SMS, and handling async events like SMS msgs that come in), but thequestions I'm asking here is more about IoT simcard providers and simcard use.Clearly, I'm not going to get very far without a simcard in the modem and I've had issues with the hologram.io cards I have. However, I generallylike the portal, i.e. dashboard, concept they have but it's lacking. So, I'm hoping others have had experience dealing and using IoT modems andcan offer some advice or recommendations. Here are some questions:1) Any general advice regarding what to look for in simcard vendor?My near term use cases include:* testing software I develop that will send short data updates over websockets, tcp/ip and udp sockets--no video, no large data, etc and not too frequently.* send and receive SMS Text messages M2M, however for testing will send/receive from on my phone* usage in typical populated areas so will have access to tier 1 providers* I don't expect more than 1 MB/mo for this near term* I'm based in US and will not be dealing with international2) I've already run into some odd things like one day my test code works with a given simcard but next day it doesn't. Hologram.io has a"dashboard" which would seem to be helpful when trying to understand why SMS texts are not arriving on my phone, but data is not updatedfrequent enough for debugging or understanding connectivity issues--dashboard says text was sent??What experience might you relate regarding this aspect of getting a project working?3) who would you recommend for a simcard provider that has good portal support for debugging sms text messaging?Thanks in advance

author: barshatriplee
author_rank: Regular Contributor
timestamp: June 09, 2023, 07:10:45 am
content: You can take a look at Twilio IoT sim:https://www.twilio.com/en-us/iot/super-sim-card

author: redkitedesign
author_rank: Regular Contributor
timestamp: June 09, 2023, 07:37:57 am
content: I've got quite some experience getting 2G and 4G modems to work in Europe, and my experience has never been that the SIM card (either the physical card or the provider) was an issue. 99% of the problems where either the documentation of the chinese modem manufacturer, or my code itself.Of course it is easy to joke that the US is a backward region without proper mobile infrastructure, but I would not directly suspect the SIM Card.When you do, there are some international providers that I have good experience with in .EU, like keepgo.com. For testing, they all provide reasonable bandwidth and data-caps for a reasonable price (compared to my hourly rate :-))

author: timbopoise
author_rank: Newbie
timestamp: June 09, 2023, 05:17:26 pm
content: "I've got quite some experience getting 2G and 4G modems to work in Europe"Does this experience include coding interface to cellular modem from small platform (SBC)? Furthermore, have you dealt with handling latent responses from AT commands?I'm learning quickly but I'm still trying to understand how to capture latent, i.e. delayed or unsolicited, response from the modem. For example when sending SMS text messagethe modem may give an immediate "OK" but a more complete response from the command comes comes later that I can use to verify results. Same issue with receivingSMS text messages how would avoid having to poll if text messages have been received over and over?A lot of this has to do with the driver or library being used, such as Espressif's esp-modem library component which supports a CMUX functionality to simultaneous maintain PPPconnections and issues AT commands. It's been hard to find answers to how this can be done with esp-modem. recently I read that they were working on a "URC" feature butthere's very little info on this and has not shown up in the release. I've seen mention of this with Telit's modems and software but no clear explanation. I think URC stands forUnanticpated Response Code (?).thx

author: timbopoise
author_rank: Newbie
timestamp: June 12, 2023, 02:41:50 pm
content: @redkitedesign

author: timbopoise
author_rank: Newbie
timestamp: June 12, 2023, 02:43:14 pm
content: @barshatripleeThanks, I'm looking into this provider now.