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) — letting a constrained IoT device exchange small Non-IP messages with an application without ever being assigned an IP address — together with 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/monitoring settings.
- Non-IP Data Delivery (NIDD) — The NIDD service: connection lifecycle, mobile-originated and mobile-terminated data, group delivery, and Reliable Data Service.
- Monitoring Events — Subscribing to and receiving 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/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 and 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 — uplink Non-IP data from the UE is delivered to the AS callback.
- Mobile-Terminated (MT) data — downlink Non-IP data from the AS is delivered to the UE, with each delivery tracked as an individual resource carrying 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 — NB-IoT exception-report indications are surfaced 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 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/HSS peers — see Diameter Service.
- Provision the external-identity → IMSI map (and any group maps) — see Identity & Group Settings.
- Ensure the T8 endpoint's TLS certificate is in place — see T8 API Endpoint.
- The Application Server then:
- creates a NIDD configuration or monitoring subscription over T8;
- receives uplink data / 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 |