Monday, October 12, 2009

NAS: Non-Access Stratum

This post is to give short description of NAS protocols, procedures and functions.
NAS is a layer for communication between Ue and Core Network (CN). This communication is transparent for underlaying Access Stratum.
NAS protocols:
  • GMM - GPRS Mobility Management
  • MM - Mobility Management
  • SM - Session Management
  • CC - Call Control
  • SS - Supplementary Services
  • SMS - Short Message Services
SM, SMS, SS and CC form a group of protocols called Connection Management.

Figure - Inter protocols communication MS side [3GPP 24.007]

SM - its functions is to activate, deactivate or modify PDP contexts which are sessions for PS traffic in UMTS/GPRS networks

Figure 1 - Simplified PDP context activation procedure

Figure 2 - Inter protocol communication for PDP context activation - MS side

CC - its functions is to establish, maintain and finally release CS calls in UMTS/GPRS/GSM networks

Figure 3- Simplified CS call proceeding

Figure 4 - Inter protocol communication for CS call setup


  1. Hey there!

    Interesting blog. I will add this blog to my blog roll. It would be nice discussing with you.

    Thanks, Santosh

  2. Hi Santosh,

    Thanks for Your opinion. I really appreciate.

    It would be really nice discussing with you since I would like to start LTE posts really soon.

    Thanks, Regards

  3. Any good books on this ? Handset side and not network side.

  4. Can anybudy tell me, What is NAS Procedure??