Good practices and guidelines for devices deployed on the EMnify network

Any customer deploying a large number of devices on the EMnify network must ensure that these devices operate following the good practices described in this article. These practices are put in place to guarantee that the devices deployed by our customers do not impact negatively other EMnify customers:

1. Back-off strategy in case the device cannot establish a data connection: If your devices have already reached the monthly limit or the application server is not reachable, your devices should introduce a random back off timer and not try to connect every few seconds. An example of a proper back off strategy would be:
   • Failed connection attempt
   • (wait 1 minute)
   • Failed connection attempt
   • (wait 10 minutes)
   • Failed connection attempt
   • (wait 30 minutes)
   • Successful connection attempt
2. Optimal IMSI switch handling: Please ensure that your devices are capable of working with multi-IMSI SIM cards. Please visit this article for additional information.
3. Connection attempt randomization: Your devices should not try to connect all of them at the same time. The attempt must be randomized. For example, if you are planning that your devices should call the application server once a day, please randomize it over a period of time.
4. Activate the SIM cards before plugging them in. Please ensure that you have activated the SIM and created a Connected Device in the portal before you plug it in. This will ensure that your device is ready to establish a data connection right after you turn it on.
5. Unplug suspended SIM cards: Even if you suspend a SIM card, your device still can try to attach to a network. In case you are not planning to use a SIM card any longer, please make sure to unplug it from the device to avoid creating unnecessary signalling events. 
6. Proper device recovery: In case of an unexpected event, your devices should be able to recover automatically. Please do not forget to set a watchdog timer that will reset your device in such cases.
7. Proper shut down procedure: Please follow the procedures specified by your modem manufacturer, so that it de-registers from the network before it powers down
8. Legal and regulatory compliance requirement: Please ensure that your devices are certified to be used in the countries where you are planning to deploy them. Certification implies that the devices meet the initial inspection requirements on many topics, especially:

   
   • Individual Network Protocols
   • TRP – Total Radiated Power
   • RSE – Radiated Spurious Emissions
   • Idle Mode Emissions,
   • Sim Specifications
   • Specific Absorption Rate, etc.

   
   The authorised organizations are guiding the process of certifications, those are empowered by commissions, industry consortiums or sometimes by the network operators. The way how the certification process is built is different across geographies. 

   
   The Certification process in North America, consisting of three layers:
   • General or governmental level, which ensures that the device is properly regulated in terms of the level of radiating the energy and radio frequency spectrum. The authorised body in the USA is the Federal Communications Commission (FCC). In many cases, depending on the behaviour of the devices, the FCC certification is enough to identify them in the networks of different operators, but that might be insufficient when it comes to some mobile network operators
   • Operating level on mobile networks, and here is the primary certification authority is PTCRB, which has mobile network operators and related industry participants, such as Rogers Telecommunication, Bell and Telus in Canada, and T-Mobile, AT&T and Sprint in the USA.
   • Certification separately by some carriers. For example, if you would like your devices to operate under the Verizon network in the USA, they need to be independently certified by this carrier. Another example is AT&T, which for some use cases might require own additional certification.

   The Certification process in Europe is from the first view seems to be relatively easy. The primary two certification process in Europe is driven by the Global Certification Forum (GCF) and European Conformity (CE).
   
   “Test once, use everywhere” is the motto of GCF, that ensures working of the devices across the different cellular networks in Europe and Worldwide, which have adopted the 3GPP Standard. Based on the use case of the M2M and IoT devices, the manufacturer can select from the different type of certifications and be compliant for it. That also affects the pricing of certification.
   
   The CE certification ensures that the devices to be launched in European countries are compliant with the requirements of the European Commission directives. This certification is applicable to many types of devices and also for radio and telecommunications equipment. Similar to GCF certification, once the CE certification is done, the device can operate in any mobile network within Europe. Based on the different test scenarios and use cases, the manufacturer might select the certification either from CE or GCF.