APN
What is an APN?
APN stands for Access Point Name. It is the link between the internet and your mobile network. When a device has an active connection and wants to connect to the internet, the APN is a parameter that needs to be configured. The carrier is then informed about the configured APN and assigns the device a specific IP address as well as a security protocol. In short: APN is the information your carrier needs in order to establish a network connection for your device. Besides internet connectivity, MMS (Multimedia Messaging Sevice) also utilizes APN.
Composition of an APN number
The Access Point Number is typically composed of two IDs:
1. The Network Identifier: This ID represents the external network to which the GGSN (Gateway GPRS Support Node) is connected to. It may also include the specific service requested by the device. For example “internet” or “MMS”
2. Operator Identifier: The operator identifier itself consists of MNC (Mobile Network Code) and MCC (Mobile Country Code)
A standard APN may look like this:
internet.mnc012.mcc695.gprs
or
mobiltel.mnc135.mcc545.gprs
However, an APN can be customized by DNS (Domain Name Service) operators. Thus APNs may also look a lot simpler like this:
Internet.verizon
or
t-mobile
These custom APNs are translated by the DNS operator in order to identify the correct network and operator identifier parameters.
Different types of APN
There are several different types of APNs, which can be categorized, based on whether they are used to connect to a public or a private network:
- Private APN: A gateway will redirect devices that have a private APN configured, to an internal private network.
- Public APN: This is the basic version of APN. If a device connects to a gateway while having public APN configured, it will be assigned an IP address to access the internet.
- APNs with a static IP: The gateway will assign a static IP address, that is chosen from the IP pool of either a public or private network.
Private access point names are mostly used, as a security measure. Since they don’t connect to the internet, there is less risk of data being intercepted by third parties.
Dynamic and Static IP in IoT
Assigning IP addresses dynamically does not work with inbound connections. Thus, Dynamic IP cannot be used to establish a connection to M2M or IoT devices, as the IP address is unknown until the device has established a connection itself. APNs with a static IP, on the other hand, can be routed and externally establish a connection.
APN Configuration
With phones, users generally don’t need to enter an APN manually in order to connect to the internet or utilize MMS features. Thanks to SMS, the APN settings can be sent to the device, once it logs onto the network. Some phones will require the user’s confirmation to apply these settings, while others will update automatically in the background.
In IoT and M2M devices, automatic APN recognition is a feature that most IoT and M2M hardware manufacturers haven’t implemented. As such, the APN needs to be configured manually. Currently, there are only a handful of exceptions to this.
Sources
https://www.androidcentral.com/which-mvnos-allow-tethering
https://cellularnews.com/mobile-network/guide-to-what-is-apn-best-ways-to-change-apn-settings-effectively/
https://www.lifewire.com/what-is-apn-access-point-name-2377408