C1011 Paging Control Stack

Paging Control Stack

The C1011 Paging Control Stack is a Linux software package that controls a response paging network, supporting multiple channels, zones, pagers, and base stations. It supports unicast and multicast communications, secure provisioning and management, and 5-second message delivery. The paging control stack is a generational update to the M41XX and M42XX paging controllers, and is specifically optimized for first-responder primary dispatch.

  • Ultra-reliable critical messaging
  • 5-second message delivery, plus confirmation and response
  • User read confirmation and multiple-choice responses
  • AES-128 message encryption with key management
  • SNPP, SMPP, SMTP, TAP, and SDP interfaces
  • Asterisk telephony platform integration
  • Active and passive standby redundancy
System Architecture

The C1011 Paging Control Stack is a 64-bit Linux software distribution. It includes three microservice modules, io, core, and rzone. Each instance installs on a commercial server running the CentOS 7 or RHEL 7 operating system.

The io module serves messaging interfaces to external clients. The core module maintains the subscriber database and message queues. The real-time rzone module handles the RF air interface, connecting to one or more base stations and providing one or more zones of Reflex coverage.

Messaging Interfaces

Through its io service module, a C1011 instance exposes the SDP, SMTP, SNPP, SMPP, TAP messaging interfaces, as well as a specialized IVR interface for use with the Asterisk telephony platform.

SDP: Sparkgap Dispatch Protocol is a socket-based text protocol for sending messages to pagers and groups of pagers, and receiving acknowledgements and responses as they happen in real time. SDP includes connection health monitoring, group membership reports, and other features relevant to primary dispatch and critical communications. A C1011 instance acts as an SDP server supporting one or more SDP clients, such as CAD systems, call centers, and alarm managers.

SMTP: Simple Mail Transfer Protocol is a push-based protocol for sending email. A C1011 instance acts as a Mail Transfer Agent (MTA), meaning it is both an SMTP client and server. Through this interface, email addresses may be assigned to pagers, which may then send and receive email messages.

SNPP: Simple Network Paging Protocol allows socket clients to send messages to pagers (RFC 1861). A C1011 instance supports level 3 SNPP, which conveys acknowledgements and responses back to the client.

SMPP: Short Message Peer-to-Peer protocol allows socket clients to send messages to pagers (smpp.org). A C1011 instance acts as a SMPP server (SMSC) and supports multiple clients (ESMEs) using protocol version 3.4.

TAP: Telocator Alphanumeric Protocol allows clients to send messages to pagers using a serial port. A C1011 instance acts as a TAP server, accepting messages from TAP clients to send to pagers.

Asterisk: C1011 instances expose the Asterisk Interface, a lightweight IVR socket protocol (crs-ivr) that can integrate into the Asterisk telephony platform as a custom application. Together, the interface and application permit telephone callers to send pager messages using a telephone dialpad.


Two C1011 instances may be configured for active redundancy, where one instance acts as a primary controller and the other acts as a secondary controller. In this case, the primary and secondary instances run on two separate machines with an IP path between them. During normal operations, the primary instance replicates its database to the secondary instance using a log shipping protocol. Base stations act as voting servers, monitoring the primary instance and prompting the secondary instance to take control upon detecting a failure.

The C1011 Paging Control Stack is available as downloadable software, with a perpetual licence based on the total number of basestations and pagers supported by the instance. The part number for the base license is CRS-C1011-STATIONS-PAGERS where STATIONS specifies the number of supported basestations and PAGERS specifies the number of supported pagers.

An existing instance may be expanded with one or more expansion licenses. The part number for the expansion license is CRS-C1011-EXPANSION-STATIONS-PAGERS where STATIONS specifies the number of additional basestations and PAGERS specifies the number of additional pagers.