Mobile Networks - Where Can My IoT Device Connect?

Hey hey, new tutorial “Mobile Networks - Where Can My IoT Device Connect?

7 billion devices and counting the Internet of Things (IoT) is everywhere! In this tutorial learn exactly how to be sure that your device can connect to a local mobile network wherever you are in the world. Quick and punchy, tells you exactly how to go about it using CellMapper, Official Coverage Maps or NPerf. I go through the process to do it for Newcastle but the same process can be followed worldwide.

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Dear Tim,
Thank you for your tutorial including corresponding Youtube video about connecting IOT devices to a 4G LTE network, where in Australia, Telstra and Vodafone are the only providers of the LTE service.

In the video you showed the Pycom device.

Three questions please.
(1) Do you need a SIM card to connect the Pycom device to the phone network? In other words, do you need a phone number?
(2) Can you ‘call’ into the IOT device and the IOT can call out?
(3) What is the speed of communications to and from an IOT device such as the Pycom?

Thank you,
Anthony of Sydney


Hey Anthony,

  1. Yes, you’ll need a valid Australian SIM, preferably with Telstra or Vodaphone, and it must be able to allow a connection to the LTE network. Should be covered in detail in this older tutorial for initial setup


  1. Excellent question, the answer is it depends on the device, what you mean by call (as it’s much easier to write scripts to send SMS rather than projects that use audio or video, in which case you may want to look into setting up a custom web server using a microprocessor and run VoIP), and whether you’re correctly connected to a network that supports it.

  2. Should be listed in the description of the device. For the Pycom GPy it’s the specs below

  • 300kbps DL
  • 375 kbps UL (LTE Cat M1 in 1.4Mhz in 1.4 Mhz, HD-FDD)
  • 40 kbps DL
  • 55kbps UL (LTE Cat M2 in 200 kHz, HD-FDD)

If there’s anything else that you need please let us know. Have a great day!


Dear Chris,
Thank you for your kind reply, it is appreciated.
I saw your ‘Getting Started’ tutorial and video and saved both to my drive…

Three and a half questions please based on this tutorial and the “Getting Started” tutorials:
(1) In the video, you mentioned two types of firmware for two types of connection from the Pycom. Is the firmware changeable to change connection type, DL or UL OR once you write the firmware for a particular connection, that’s it, you cannot change it?

(2) From the video and the data rates whether DL or UL. Generally is this the communications method that my smartphone uses to view webpages or conduct other internet communications such as for example FTP or use any of the 65536 ports for a given IP address for my own communications?

(2A) The reason for asking this question is to take into consideration data charges by the phone provider.

(3) I don’t live in Newcastle but use Newcastle as an example. If I want two-way communications between two Pycom-connected devices, one in Callaghan and the other in Merewether we’d need to know the IP addresses which changes for a particular connection.

Yes I do know that you need to write a protocol to find out the IP address each time a new connection is made.

Thank you
Anthony of Belfield NSW 2191

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Hi Anthony,

The firmware alternatives Chris mentioned in the older video is for whether you’re connecting using LTE CAT M1, or NB-IoT (aka NB1). These are different technologies hence the need for different firmware for the radio. They can both Upload (UL) and Download (DL) data - infact all internet connections require bidirectional communication. It’s a fundamental requirement of HTTP and most other internet protocols!

However, in full duplex, devices can transmit (UL) and receive (DL) simultaneously. This is the case for LTE-CAT M1. In a half-duplex communication standard like LTE CAT NB1, devices must take turns transmitting and receiving.

I’m not really clear on your second question, but most ‘4G’ phones will use LTE Advanced. LTE is the original 3G technology, LTE Advanced is the 4G, and LTE Advanced Pro is a 5G technology. All three are different, but confusingly all three are often referred to as LTE!

But yes, whatever technology you use, if you’re consuming data your network provider will count it towards your data usage. You’d need to check your Critical Information Summary (CIS) or with your provider as to whether uploaded data is counted against your usage.

And regarding the third question, yes, but you can use Dynamic DNS - or an alternative:

This way you only need to know the name of your device, not its IP.