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标题: ss7 singal and voice data associate meth [查看完整版帖子] [打印本页]

时间: 2025-7-4 21:25

作者: carlff 标题: ss7 singal and voice data associate meth

the below materical srouce from Chatgpt, for reference only.

To associate signaling information (likeSS7 messages) with voice (media) data in an SS7-based call, you need tounderstand the separation of signaling and media in circuit-switched networks.Here's a clear breakdown of how this works and how to correlate the two:

🔧 BasicSS7 Call Structure

SS7 signaling is used for call setup,management, and teardown, while the actual voice traffic is carried over aseparate TDM path (usually using PCM timeslots in E1/T1 circuits).

SS7 separates:

Signaling (control plane): Handled by SS7protocols (e.g., ISUP)

Media (user/data plane): Handled by theactual bearer circuits (e.g., TDM timeslot or VoIP RTP stream)

✅ Steps toAssociate Signaling Info to Voice Path

1. Track ISUP Messages

Focus on the ISUP (ISDN User Part)messages, especially:

ISUP Message Purpose

IAM (Initial Address Message) Starts the call. Contains key bearerinfo.

ACM (Address Complete Message) Indicates the call is progressing.

ANM (Answer Message) Call answered – bearer path is established.

REL/RLC Callrelease/clear

Look at these key parameters in IAM:

CIC (Circuit Identification Code):Identifies the TDM channel being used

Calling / Called Party Numbers

Bearer Capability / Nature of ConnectionIndicators

2. Use the CIC to Trace the Voice Circuit

The CIC, alongwith the Point Code of the signaling link, maps to a specific E1/T1 timeslotcarrying voice.

For example:

CIC = 31 → corresponds to E1 timeslot 16 (depends on switch mapping)

So: Voice data flows on E1 line X, timeslotY

3. Monitoring Tools or Probes

In practice, correlation is done using:

SS7 probes (e.g., Wireshark + SS7 plugin,Tektronix, or VoIPMon)

Softswitch logs / Media Gateway logs(MGCF/MGW)

Call Detail Records (CDRs) with CIC orbearer mapping

4. If VoIP is Involved (VoIP Interworking)

In NGN or IMS, SS7 signaling maps to SIPand voice goes over RTP.

Association process:

SS7 ISUP (with CIC) → SIP INVITE (with SDP)

MGCF translates ISUP to SIP and connects toRTP stream

Look into MGW/MGCF logs to correlate CIC ↔RTP stream IP/port

🔎Example (Simplified)

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[SS7 Signaling]

IAM: Calling=1234, Called=5678, CIC=12

→ Check CIC=12 → Maps to E1=3, Timeslot=13

[Voice Path]

→ Voice goes over E1-3/TS-13

→ PCM data carries G.711 or similar codec

→ Or, if interworked to SIP/RTP:

CIC=12 ↔ MGCF ↔ SIP INVITE → RTP: 10.1.1.10:4000 ↔ 10.1.1.20:4002

🔚Summary

To associate SS7 signaling with voice data:

Extract CIC from IAM

Map CIC to TDM bearer (timeslot) or RTPstream

Use MGCF logs or probes to trace media

Use SIP-SDP or RTP analysis if IPinterconnect is used

时间: 2025-7-5 14:50

作者: 不吹不黑

翻译一下！

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