Bearer
A logical transport channel in LTE/EPC with a defined QoS level (QCI). Dedicated bearers carry specific service flows, while the default bearer provides always-on connectivity.
A bearer is a pipe with a promise. It's the end-to-end path your packets take — from the device through the eNB and gateways out to the P-GW — but the important part is the QoS attached to it, identified by a QCI (QoS Class Identifier) that pins down priority, acceptable delay, and tolerable packet loss.
The split you actually work with day to day:
- Default bearer — set up at attach and kept alive for the whole session. It's best-effort (typically a non-guaranteed bit rate, QCI 9 for general internet) and gives you always-on connectivity.
- Dedicated bearer — created on demand for traffic that needs special treatment. The classic case is VoLTE voice on QCI 1, a guaranteed-bit-rate bearer so your call doesn't compete with someone's download.
A single device can hold several bearers at once — one for browsing, one for a voice call, each with its own QoS. The whole point of the bearer concept is that the network can treat a latency-sensitive voice packet completely differently from a bulk download, even on the same connection. (5G keeps the idea but reworks it as QoS flows mapped onto a PDU session.)
Frequently asked questions
- What's the difference between a default bearer and a dedicated bearer?
- The default bearer is created automatically when you attach and lasts for your whole session, giving best-effort, always-on connectivity. A dedicated bearer is set up only when needed — for a specific service that requires guaranteed quality, like a VoLTE call — and torn down when that service ends. The default bearer is your baseline pipe; dedicated bearers are added on top for traffic that needs protected QoS.
Related terms
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