OmniMSC is a 3GPP-compliant Mobile Switching Center server developed by Omnitouch. It provides circuit-switched voice, SMS, supplementary services, and mobility management for GSM and UMTS radio access networks, with interworking toward SIP, ISUP, and LTE via CS Fallback.
OmniMSC implements the MSC server role defined in 3GPP TS 23.002, with protocol support spanning TS 24.008 (CC/MM/SS), TS 29.002 (MAP), TS 29.078 (CAP), TS 23.272 (SGs/CSFB), RFC 3261 (SIP), and ITU-T Q.767 (ISUP).
Architecture Overview
MSC-A is the central connection manager. Each subscriber attachment creates an MSC-A process that owns the SCCP connection and coordinates the VLR, CC FSM, SMS, USSD, and supplementary service subsystems for that subscriber. External interfaces fan out from these subsystems to the network elements shown on the right.
Features
| Category | Capabilities |
|---|
| Voice | MO and MT calls, call hold, multi-party conference (MPTY), explicit call transfer (ECT), emergency calls with PSAP routing |
| SMS | MO-SMS and MT-SMS via MAP to SMSc, SMS over SGs for CSFB-attached subscribers |
| USSD | Network-initiated and mobile-initiated USSD, relay to external USSD gateway or local handling |
| Supplementary Services | Call forwarding (CFU/CFB/CFNR/CFNRC), call barring (BAOC/BOIC/BAIC), call waiting, CLIP/CLIR |
| CAMEL | CAMEL Phase 2 service control via CAP interface to gsmSCF, IDP triggering, BCSM event monitoring |
| CS Fallback | SGs interface to MME, combined attach, paging via SGs, SMS over SGs |
| MSC Pool | NRI-based TMSI allocation, pool-area load distribution, non-broadcast LAI |
| Emergency Calls | Configurable emergency number table, SIM-less call support, location-based PSAP routing |
| Media | MGCP call agent for media gateway control, codec negotiation, conference bridge resources |
| Trunking | SIP peers (UDP/TCP/TLS) and ISUP trunk groups with full circuit management |
| Monitoring | Prometheus metrics, web control panel (LiveView), CDR generation |
Documentation
Core
| Document | Description |
|---|
| Configuration Reference | Complete parameter documentation for all subsystems |
| Routing | Number analysis, route table configuration, trunk selection logic |
| Document | Description |
|---|
| Call Flows | Sequence diagrams for MO/MT voice calls, hold, conference, DTMF |
| SIP Trunking | SIP peer configuration, re-INVITE handling, session timers, DTMF relay |
| ISUP Trunking | ISUP/SS7 trunk groups and circuit management procedures |
| Media & Codecs | MGCP gateway control, codec negotiation, conference bridge |
Messaging & Services
| Document | Description |
|---|
| SMS | MO/MT SMS routing, delivery attempts, and MAP procedures |
| USSD | USSD relay to external gateways and local handling |
| Supplementary Services | Call forwarding, call barring, call waiting, CLIP/CLIR, MPTY conference |
Interworking
| Document | Description |
|---|
| MAP Operations | HLR and SMSc MAP procedures (location update, authentication, SMS routing) |
| CAMEL & CAP | CAMEL service control, Initial DP, BCSM event handling |
| SgS & CSFB | CS Fallback via SGs interface to MME, combined attach, paging |
Security & Identity
| Document | Description |
|---|
| Authentication & Security | AKA vectors, cipher mode negotiation, TMSI reallocation |
| MSC Pool | MSC-in-Pool operation, NRI-based TMSI, pool-area configuration |
Operations & Management
Documentation by Role
Operators
Day-to-day monitoring and incident response. Start here:
- Control Panel — real-time subscriber, call, and alarm visibility
- Troubleshooting — symptom-based lookup for common problems
- Metrics & Monitoring — Prometheus dashboards and alerting rules
Integrators
Connecting OmniMSC to the surrounding network. Start here:
- Configuration Reference — all parameters for every interface
- SIP Trunking — SIP peer setup, codec profiles, failover
- ISUP Trunking — SS7 trunk group provisioning
- MAP Operations — HLR and SMSc connectivity
- SgS & CSFB — MME integration for CS Fallback
Network Planners
Capacity planning and network design. Start here:
- Routing — number analysis and route table design
- MSC Pool — pool dimensioning, NRI allocation, rolling upgrades