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Soft switching architecture and management
Short answer
Soft switching separates software-based call control (softswitch) from hardware media gateways. The architecture includes a softswitch controlling media and signalling gateways via H.248/MGCP and SIGTRAN over an IP core. Functions include call control, routing, signalling interworking, and CDR generation. Management uses FCAPS for fault, configuration, accounting, performance, and security.
What is soft switching? Describe its architecture, functions and management.
Soft switching
Soft switching is a switching method in which call control is done by software on a general-purpose server (the softswitch or call agent), separate from the hardware that carries the media. The softswitch controls media gateways over an IP network, so one software platform can handle PSTN, VoIP and mobile calls. It is the core of next-generation networks (NGN).
Architecture
+---------------------------------------------+
| Application layer: app servers, IN, billing |
+----------------------+----------------------+
| SIP / APIs
+----------------------+----------------------+
| Control layer: SOFTSWITCH (call agent/MGC) |
+-----+----------------+---------------+------+
| H.248/MGCP | SIGTRAN | SIP
+-----+-----+ +------+-----+ +-----+-----+
| Media | | Signalling | | IP phones |
| gateway | | gateway | | / SIP UA |
+-----+-----+ +------+-----+ +-----------+
| transport layer: IP/MPLS core |
PSTN trunks SS7 network
- Softswitch / Media Gateway Controller (MGC): call control, routing, signalling interworking, number analysis.
- Media Gateway (MG): converts TDM voice (PSTN) to RTP/IP packets and back, under the control of the MGC via H.248/Megaco or MGCP.
- Signalling Gateway (SG): converts SS7 signalling to IP (SIGTRAN, M3UA/SCTP) for the softswitch.
- Application server: value-added services (voicemail, prepaid, conference, IN services).
- Media server: tones, announcements, IVR, conference mixing.
- Transport (IP/MPLS) network that carries both media and signalling.
Functions
- Call setup, supervision and release (call control).
- Signalling interworking: SS7, ISUP, SIP, H.323, H.248.
- Routing and number translation.
- Control of media gateways and allocation of resources.
- Service invocation through application servers.
- Generation of CDRs for billing; authentication and authorisation.
Management
The softswitch network is managed by an OSS/NMS using FCAPS:
| Area | Task |
|---|---|
| Fault | alarms, failover, redundancy |
| Configuration | gateways, routes, numbering, users |
| Accounting | CDR collection, billing |
| Performance | traffic, QoS, delay, packet loss |
| Security | access control, encryption, firewalls |
Management uses SNMP and web/CLI interfaces, often remotely.
Advantages: lower cost, open interfaces, easy addition of new services, scalability, and one platform for voice and data.
✓ Answer checked by Claude Opus 5.5 (high effort)
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