AS-SIP

This is a work in progress. @John Shaheen

AS-SIP incorporates essential DoD features:

Multi-Level Precedence and Preemption (MLPP):

Communications resource priorities for SIP (RFC 4412)
Precedence and Preemption assuring end-to-end communications connectivity
MLPP Authentication and Authorization

Secure Real-Time Transport Protocol (SRTP):

Enables encrypted communications

Transport Layer Security (TLS):

Enables encrypted communications

Vocal's Assured Services SIP (AS-SIP) UC SIP (disa.mil) Errata: as-sip2013.pdf (disa.mil)

It requires SRTP and TLS on top of RFC 3261 (SIP) which we do support; but also lists states it needs to support Multi-Level Precedence and Preemption (MLPP) (RFC 4412). This RFC defines a priority system for communication traffic. RFC 4412 states:

This document defines (Section 3) two new SIP header fields for communications resource priority, called 'Resource-Priority' and 'Accept-Resource-Priority'.

Precedence Authorization levels work in practice:

Definition:
- Precedence Authorization levels are used to prioritize communication resources based on the urgency and importance of messages.
- These levels span from Routine (lowest priority) to Executive Override (highest priority).
Practical Application:
- In scenarios such as military or emergency services, Precedence Authorization ensures efficient resource allocation during communication.
- Here’s how it works:
  - Routine: Non-urgent messages, such as administrative announcements.
  - Priority: Important but not critical messages.
  - Immediate: Urgent messages requiring prompt attention.
  - Flash: Critical messages that need immediate action.
  - Override: Reserved for high-ranking officials or emergencies.
Example:
- Imagine a military operation:
  - A Routine message might be an inventory update.
  - A Flash message could signal an imminent threat.
  - An Executive Override message would come directly from a top commander.