OmniSCEF Operations Guide
OmniSCEF is Omnitouch's Service Capability Exposure Function (SCEF) for Cellular-IoT / NB-IoT. It exposes network capabilities to third-party Application Servers (the SCS/AS) over the T8 RESTful API, and terminates the T6a Diameter interface towards the MME. Its primary role is Non-IP Data Delivery (NIDD). NIDD lets a constrained IoT device exchange small Non-IP messages with an application without an IP address. It also provides Monitoring Events (reachability, loss of connectivity, location, and related event reporting).
Documentation
- Configuration Reference: every configuration parameter for the Diameter service, the T8 API endpoint, and identity and monitoring settings.
- Non-IP Data Delivery (NIDD): the NIDD service. This covers connection lifecycle, mobile-originated and mobile-terminated data, group delivery, and Reliable Data Service.
- Monitoring Events: how to subscribe to and receive UE monitoring events over T8 and T6a.
- Troubleshooting: common operational problems and their resolution.
Architecture Overview
OmniSCEF is a translation and correlation point:
- Northbound (T8), the Application Server addresses a device by an External Identifier
(
user@domain) or MSISDN, over HTTPS and JSON, per 3GPP TS 29.122. - Southbound (T6a), the MME addresses the subscriber by IMSI and EPS Bearer Identity (EBI), over Diameter, per 3GPP TS 29.128.
- OmniSCEF holds the binding between the two identity spaces and the associated session state.
Interfaces
| Interface | Peer | Transport | Protocol | Specification |
|---|---|---|---|---|
| T8 | SCS/AS | HTTPS (default port 8443, under /api) | REST / JSON | TS 29.122 |
| T6a | MME / SGSN | TCP and SCTP (default port 3868) | Diameter | TS 29.128 |
| T6a (monitoring) | HSS / serving node | TCP / SCTP | Diameter (CIR/RIR) | TS 29.128, TS 29.336 |
The Diameter side reuses the standard T6a application (Application-Id 16777346). NIDD and Monitoring-Event command families both run on this application. See Reference Tables for the command and result codes.
Features Overview
Non-IP Data Delivery (NIDD)
- Configuration lifecycle: the AS provisions a device (or group) for NIDD. OmniSCEF resolves the external identity to an IMSI. OmniSCEF then authorises the T6a connection.
- Connection management: the MME establishes and releases the T6a connection as the UE attaches and detaches. The AS can also trigger a release by deleting the configuration.
- Mobile-Originated (MO) data: OmniSCEF delivers uplink Non-IP data from the UE to the AS callback.
- Mobile-Terminated (MT) data: OmniSCEF delivers downlink Non-IP data from the AS to the UE. It tracks each delivery as an individual resource that carries its delivery status.
- Group NIDD: a single downlink to a group fans out to every member device.
- Reliable Data Service (RDS): optional port-multiplexed framing of the Non-IP payload.
- MO exception data: OmniSCEF surfaces NB-IoT exception-report indications to the AS.
Monitoring Events
- Subscription management: the AS subscribes to a monitoring event for a device or group.
- Event reporting: the serving network reports events (reachability, loss of connectivity, location, roaming, and more). OmniSCEF delivers each event to the subscribing AS.
See NIDD and Monitoring Events for the detailed message flows.
Identity Resolution
The Application Server never sees an IMSI. OmniSCEF maps the AS-facing identity to the network-facing identity:
Resolution is driven by operator-provisioned maps (see Identity & Group Settings). The binding to a live T6a connection is completed when the MME establishes the connection for that IMSI.
Quick Start
- Provision the OmniSCEF Diameter identity and the MME and HSS peers. See Diameter Service.
- Provision the external-identity to IMSI map (and any group maps). See Identity & Group Settings.
- Put the T8 endpoint's TLS certificate in place. See T8 API Endpoint.
- The Application Server then:
- creates a NIDD configuration or monitoring subscription over T8;
- receives uplink data and event reports on its notification callback;
- sends downlink data over T8.
Reference Tables
T6a Diameter Commands
| Command | Abbrev. | Code | Direction | Purpose | Reference |
|---|---|---|---|---|---|
| Connection-Management-Request/Answer | CMR/CMA | 8388732 | MME ↔ SCEF | Establish / release a NIDD connection | TS 29.128 §5.3 |
| MO-Data-Request/Answer | ODR/ODA | 8388733 | MME → SCEF | Uplink (mobile-originated) Non-IP data | TS 29.128 §5.4 |
| MT-Data-Request/Answer | TDR/TDA | 8388734 | SCEF → MME | Downlink (mobile-terminated) Non-IP data | TS 29.128 §5.5 |
| Configuration-Information-Request/Answer | CIR/CIA | 8388718 | SCEF → HSS/MME | Arm a monitoring event | TS 29.128 §5.6 |
| Reporting-Information-Request/Answer | RIR/RIA | 8388719 | HSS/MME → SCEF | Report a monitoring event | TS 29.128 §5.7 |
Diameter Result Codes
| Code | Name | Meaning | Reference |
|---|---|---|---|
| 2001 | DIAMETER_SUCCESS | Request accepted / data delivered or buffered | RFC 6733 §7.1.1 |
| 3001 | DIAMETER_COMMAND_UNSUPPORTED | Command not supported on this application | RFC 6733 §7.1.3 |
| 3002 | DIAMETER_UNABLE_TO_DELIVER | No matching handler / application | RFC 6733 §7.1.3 |
| 5001 | DIAMETER_ERROR_USER_UNKNOWN | No NIDD configuration exists for the subscriber | TS 29.128 §6.5 |
| 5012 | DIAMETER_UNABLE_TO_COMPLY | Request could not be processed (e.g. UE/AS unreachable) | RFC 6733 §7.1.5 |
Application ID
| ID | Interface | Description | Reference |
|---|---|---|---|
| 16777346 | T6a/T6b | SCEF ↔ MME/SGSN NIDD and Monitoring Events | 3GPP TS 29.128 |