01
SIP starts the call
SIP handles registration, call invitation, ringing, answer, routing changes and call termination.
M5 Technologies & Mediatrix VoIP Academy
RTP Explained: the voice stream behind every VoIP call.
RTP is the protocol that carries the actual voice audio in a VoIP call. SIP starts the call. RTP carries the conversation.
M5 Technologies and Mediatrix help enterprises, operators and critical infrastructure teams understand how RTP works, how it interacts with SIP, why media paths matter, and how Sentinel SBCs and Mediatrix gateways help control real-time voice traffic.
SIP
Sets up the call: user registration, INVITE, ringing, answer, routing and hang-up.
CALL CONTROL → MEDIA STREAM
RTP
Carries the live audio packets between phones, gateways, SBCs, PBXs and cloud voice platforms.
AudioVoice payload
TimingReal-time flow
QoSDelay sensitive
SRTPSecure media
Simple Explanation
RTP is not the call setup. RTP is the media stream.
In a VoIP call, SIP and RTP work together. M5 Technologies and Mediatrix often explain it this way: SIP is the signalling layer; RTP is the voice media layer.
02
RTP carries the audio
RTP transports the real-time voice packets that make up the actual conversation between endpoints.
03
SRTP secures RTP
When media encryption is required, SRTP is used to protect the RTP voice stream.
Why Customers Need to Understand RTP
Voice quality depends heavily on the RTP path.
Customers often focus on SIP trunks, Teams voice or PBX migration, but the real user experience depends on the RTP media stream. If RTP is delayed, blocked, misrouted or poorly prioritized, calls may suffer from one-way audio, packet loss, jitter or dropped media.
- RTP must pass correctly through firewalls, NAT, SBCs and gateways.
- Media paths must be planned for latency, jitter and packet loss.
- SRTP may be required for secure voice media.
- SBCs help anchor, control and normalize media between networks.
Layer
What It Does
Customer Impact
SIP
Sets up and controls the call session.
Determines whether calls can connect and route properly.
RTP
Carries the actual voice audio packets.
Determines call quality, audio flow and real-time performance.
SRTP
Encrypts the RTP media stream.
Helps protect conversation confidentiality.
Mediatrix Voice Infrastructure
Where M5 Technologies and Mediatrix fit in the RTP path.
RTP is sensitive to routing, firewalls, NAT traversal, codec selection and network quality. M5 Technologies and Mediatrix help customers control these media flows through SBCs, gateways and embedded voice software.
Sentinel SBC
Anchors and controls voice media between SIP trunks, Teams voice, PBXs, UC platforms and carrier networks.
Mediatrix Gateways
Bridge analog or digital telephony to IP voice while handling SIP and RTP media in migration projects.
DGW Software
Provides routing, configuration and operational controls for Mediatrix and Sentinel deployments.
M5T Software
Supports embedded voice and SIP/RTP communications for OEM products and specialized devices.
Recommended M5 / Mediatrix Products
Products that help manage SIP and RTP voice media.
M5 Technologies and Mediatrix provide SBCs, gateways and embedded software for secure, reliable and interoperable real-time voice communications.
Sentinel SBC CS
Virtual SBC for SIP and RTP control across Microsoft Teams, SIP trunks, cloud voice and operator networks.
View ProductSentinel 400 SBC
Enterprise SBC and gateway platform for SIP signalling, RTP media control, migration and secure voice edge.
View ProductM5T SIP Client Engine
Embedded SIP and real-time communications software for OEM products that need voice media capabilities.
View ProductRTP FAQ
Common questions about RTP in VoIP.
What is RTP?
RTP stands for Real-time Transport Protocol. In VoIP, it carries the actual voice audio packets during the call.
Is RTP the same as SIP?
No. SIP controls the call session. RTP carries the real-time audio media after the call is established.
Why do calls sometimes have one-way audio?
One-way audio can happen when RTP media is blocked, misrouted or affected by firewall, NAT, SBC or network configuration issues.
What is the secure version of RTP?
SRTP is the secure version of RTP. It is used to encrypt the voice media stream.
Voice Media Assessment
Need to solve RTP, one-way audio or voice quality issues?
Ask M5 Technologies to review your SIP/RTP architecture, Microsoft Teams Direct Routing, Mediatrix gateway deployment or Sentinel SBC media path.
- Review RTP media path and NAT traversal.
- Validate SIP trunk and SBC media handling.
- Identify causes of one-way audio or jitter.
- Plan secure SRTP and Mediatrix gateway deployment.