When you make or receive a call through a business phone system, multiple technologies work together to ensure the call is connected and the conversation flows smoothly. Two of the most important components are the PBX (Private Branch Exchange) and RTP (Real-time Transport Protocol).
Although they work together during every call, they perform completely different roles:
- PBX manages and routes the call.
- RTP carries the voice between the caller and the recipient.
What is a PBX?
A Private Branch Exchange (PBX) is the call control system that manages incoming and outgoing calls. It determines how calls should be handled based on your organization's configuration.
The PBX is responsible for:
- Receiving incoming calls.
- Routing calls to extensions, users, ring groups, or call queues.
- Playing IVR (Phone Tree) menus.
- Applying business hours and holiday schedules.
- Forwarding or transferring calls.
- Sending unanswered calls to voicemail.
- End the call when the conversation is complete.
Think of the PBX as the brain of the phone system. It makes all the routing decisions but does not carry the actual voice conversation.
What is RTP?
Real-time Transport Protocol (RTP) is the protocol responsible for transmitting voice during a phone call.
After the PBX connects the call, RTP creates a media stream between the caller and the recipient, allowing both parties to hear each other in real time.
RTP is responsible for:
- Delivering voice packets between participants.
- Supporting two-way audio communication.
- Maintaining low latency for natural conversations.
- Working with audio codecs such as G.711 and Opus.
Unlike the PBX, RTP does not decide where the call goes; it only transports the audio after the connection has been established.
How PBX and RTP Work Together
The following sequence shows how both components participate during a call:
PBX vs. RTP
PBX |
RTP |
|---|---|
| Controls and routes calls | Transmits voice during the call |
| Processes call routing rules | Carries audio packets |
| Handles IVRs, queues, extensions, and transfers | Supports real-time voice communication |
| Active throughout the call lifecycle | Active only while audio is being exchanged |
| Focuses on call management | Focuses on media delivery |
Support / Contact
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