![](https://emergencyservicestimes.com/wp-content/uploads/2025/05/ESS-Button-resized.png")
Emergency services agencies moving towards 4G and 5G mission-critical broadband networks now have a defined, interoperable way to alert and mobilise on-call personnel, following the publication of new Broadband Callout specifications by The Critical Communications Association (TCCA).
Callout services are a core element of emergency response operations, enabling control room dispatchers to rapidly notify first responders of incidents, share short situational details and confirm who is available to respond. While this capability has been standardised in TETRA networks for more than a decade, no equivalent specification has existed for 3GPP-based broadband mission-critical networks, until now.
Developed by a task force within TCCA’s Critical Communications Broadband Group (CCBG), the new specifications define how callout should operate over 3GPP Mission Critical (MCX) services, including Mission Critical Push-to-Talk (MCPTT), Mission Critical Data (MCData) and Mission Critical Video (MCVideo).
Two new specifications published
The work has resulted in two key documents: the Mission Critical Broadband Callout Service Overview, which sets out requirements and use cases, and the Mission Critical Broadband Callout Service Definition, which provides the detailed technical specifications.
Broadband Callout is defined as a two-way paging service that allows dispatchers to select specific first responders for an incident and send callout alerts containing a description of the situation. Users can then respond directly, indicating whether they are available to attend.
In TETRA networks, callout relies on Short Data Service (SDS) and voice communications. The broadband equivalent is fully aligned with 3GPP MCX standards, using MCData SDS alongside MCPTT to preserve fast, lightweight alerting while enabling richer interaction when required.
Simple and full callout options
The new specifications define two levels of broadband callout functionality. Simple Callout uses text messages only to alert users and collect responses, providing a straightforward replacement for traditional paging workflows. Full Callout adds a two-way information phase, allowing dispatchers and responders to communicate via an MCPTT callout group and exchange MCData text about the incident while the callout is still in progress.
Task force leader Hans Petter Naper of the Norwegian Communications Authority (Nkom) said the goal was to replicate the proven efficiency of TETRA callout while taking advantage of broadband capabilities.
“Similar to TETRA callout, Broadband Callout is a lightweight service designed for efficient alerting and user responses, and with added features to take advantage of broadband capabilities,” he said. “Callout is a vital part of dispatch functionality, and a widely adopted and interoperable callout service should be part of broadband mission-critical networks.”
Interoperability across agencies and borders
TCCA first published TETRA callout specifications in 2009, enabling interoperability between dispatch systems and radio terminals from different manufacturers. The association says the new broadband specifications are intended to deliver the same level of vendor-independent operation for mission-critical LTE and 5G networks.
“With mission-critical broadband callout specifications, TCCA complements the 3GPP standards to enable further mission-critical functionality over 3GPP MCX networks in a common way,” said CCBG chair Tero Pesonen. “This is a significant step we are taking in serving the critical communications community.”
Once implemented, the specifications will allow first responders to be called out regardless of who supplies the MCX clients or dispatch systems, provided products conform to the standard. The callout service also supports mobilising users across different agencies, user groups and national boundaries, an increasingly important requirement for large-scale incidents and cross-border cooperation.
For emergency services planning a transition from TETRA to broadband, the new standard aims to ensure that a critical operational capability is not lost in the move to next-generation networks.
To read similar articles, check out our Technology channel
