servingNodeTypeIndicator  IE 

This parameter indicates by its presence that the subscriber's serving node is an MME (which is either stand alone or combined with an SGSN) and it indicates by its absence that the subscriber's serving node is an SGSN (which is either stand alone or combined with an MME).
Reference: TS 29.002-f30   View

Type:

  Null

Value Length:

  1 .. 4


Containing Messages
UpdateGprsLocationArg