An Access Point Name (APN) acts as a gateway between a mobile network and another network, typically the Internet. It's a crucial setting on mobile devices for enabling access to the Internet and other services. Here's a detailed look at the APN's role in mobile telecommunications, including when a UE does not request a specific APN.
- Case 1: UE Requests a Specific APN
- Connection Request: The device sends a request with a specified APN from its settings, indicating the type of service it is trying to access.
- APN Evaluation: The network evaluates the specified APN to determine the correct gateway for routing the device's data traffic, ensuring the device is authorized for the requested service.
- Gateway Routing: The network routes the data traffic to the specified gateway, serving as the interface to the external network or service.
- IP Address Allocation: The gateway assigns an IP address to the device, facilitating communication with the external network.
- Data Session Establishment: A data session is established with the appropriate settings based on the APN's configuration, allowing data transfer.
- Data Transfer: The device can send and receive data, accessing the requested internet services or other networks.
- Case 2: UE Does Not Request a Specific APN
- UE Network Attachment and Default APN Selection: If the UE does not specify an APN, the network assigns a default APN based on the subscriber's profile and the service subscription.
- Session Establishment with Default APN: The network initiates a session using the default APN, which includes setting up data bearers and allocating an IP address to the UE.
- IP Address Allocation: Similar to the specific APN case, the P-GW associated with the default APN allocates an IP address to the UE for data communication.
- Accessing Services: With the default APN configured and the data bearer activated, the UE accesses the internet and other network services using the assigned IP address.