VectorCore MCX

mcxas is a Go-based MCX IMS Application Server targeting MCOP SDK 3.0 and 3GPP Release 13 MCPTT interoperability. It combines SIP call control, CMS/GMS XCAP services, MCPTT media observation and relay, persistence, and an OAM REST API/UI in one binary.

Note: This project is a work in progress. A fully working implementation should not be expected yet.

Requirements

• Go 1.25 or newer
• Node.js and npm (to build the embedded React UI)
• make

The optional SIP smoke test also requires nc and socat.

Build and test

make
make test

make runs the UI build and then builds bin/mcxas. To rebuild only the Go binary while retaining the existing web/dist assets, run make build.

For UI development, start the API separately and run:

make dev-ui

The Vite development server proxies /api, /metrics, and /health to localhost:8080.

Configure and run

Edit config.yaml for the deployment network before starting the server. The checked-in file contains lab-specific advertised addresses and MCX identities.

./bin/mcxas -c config.yaml

Command-line flags:

• -c <path> selects the YAML configuration file (default config.yaml).
• -d enables debug-level logging, overriding log.level.
• -v prints the application version and exits.

If the selected configuration file does not exist, built-in defaults are used. Invalid or unreadable configuration files cause startup to fail.

Listeners and defaults

Service	Configuration	Default
OAM API/UI	api.listen	:8080
CMS/XCAP	cms.listen	:8100
SIP UDP	sip.udp_listen	:5060
SIP TCP	sip.tcp_listen	:5060
RTP UDP	media.listen_host + media.audio_port	0.0.0.0:40000
RTCP UDP	media.listen_host + media.rtcp_port	0.0.0.0:40001
MCPTT floor control UDP	media.listen_host + media.floor_control_port	0.0.0.0:40002

Important configuration behavior:

• sip.advertise_host, sip.advertise_port, and sip.transport form the advertised SIP Contact and Record-Route URIs.
• sip.record_route defaults to true.
• sip.notify_route_set_order defaults to preserve, which retains the learned IMS route order for in-dialog NOTIFY requests.
• sip.options.enabled enables periodic outbound OPTIONS on learned SIP routes; sip.options.interval defaults to 30s.
• cms.enabled controls the XCAP server. cms.xcap_root is derived from the advertised SIP host and CMS port when omitted.
• media.enabled controls all three media listeners.
• media.advertise_host defaults to sip.advertise_host.
• media.direction defaults to sendrecv.
• media.floor_auto_grant enables floor grant, deny, idle, and queue-position responses. The grant duration defaults to 30 seconds.
• media.log_packets enables sampled packet logging, controlled by media.log_packet_interval.
• database.driver accepts sqlite, postgres, or postgresql.
• database.dsn defaults to mcxas.db.
• log.file defaults to mcxas.log; log.level accepts debug, info, warn, or error.
• IMS realm and MCX identities/endpoints are derived from ims.mcc, ims.mnc, and the advertised host when their explicit values are omitted.

OAM endpoints

• UI: http://127.0.0.1:8080/ui/
• API documentation: http://127.0.0.1:8080/api/v1/docs
• OpenAPI document: http://127.0.0.1:8080/api/v1/openapi.json
• Health check: http://127.0.0.1:8080/health
• Prometheus metrics: http://127.0.0.1:8080/metrics
• XCAP root: http://127.0.0.1:8100/xcap-root/

The REST API provides status and CRUD operations for users, groups, static memberships, and runtime affiliations, plus read-only registration, call, and SIP dialog views under /api/v1.

The UI exposes dashboards for users, groups, memberships/affiliations, registrations, and calls.

Current implementation

SIP signaling:

• UDP and TCP listeners
• inbound and optional periodic outbound OPTIONS
• PUBLISH for poc-settings and presence-based group affiliation
• SUBSCRIBE for presence and xcap-diff, with initial in-dialog NOTIFY
• third-party REGISTER and de-registration tracking with automatic expiry
• INVITE, ACK, BYE, and RFC 3261 cancellation handling
• in-dialog UPDATE and INFO
• multipart MCPTT-info and SDP extraction
• Record-Route/Contact construction and persisted dialog route state
• group-call membership admission and outbound INVITE/BYE legs to other registered group members

CMS/GMS and identity:

• XCAP GET, PUT, and DELETE
• generated Release 13 UE initial configuration, UE configuration, MCPTT user profile, service configuration, and OMA group documents
• content ETags and xcap-diff document notifications
• development IdMS authorize/token callback shim at /idms/*

The IdMS shim issues unsigned development JWTs and is not a production authentication service.

Media and floor control:

• SDP answers advertising RTP, RTCP, and MCPTT floor-control ports
• RTP/RTCP/floor packet matching to active calls
• RTP packet, loss, jitter, byte, and rejected-packet accounting
• RTP relay between active legs of the same group call
• MCPTT floor request/grant/deny/release/idle and queue-position handling
• single-holder enforcement and rejection of RTP from a non-holder SSRC
• implicit floor grant through the SDP answer for the current MCOP client flow

Persistence supports SQLite and PostgreSQL for users, groups, memberships, affiliations, CMS documents, publications, subscriptions, dialogs, registrations, and calls.

Smoke test

With mcxas running, exercise TCP/UDP OPTIONS plus sample multipart PUBLISH and INVITE requests:

./scripts/sip-smoke.sh [host] [port] [ims-realm]

Defaults are 127.0.0.1, 5060, and ims.mnc435.mcc311.3gppnetwork.org.

Installation

sudo make install

This installs the binary under /opt/vectorcore, copies the initial configuration to /opt/vectorcore/etc/mcxas.yaml if it does not already exist, and enables and starts vectorcore-mcxas.service. Build the UI with make ui before installation if web/dist is not already present.