LTE: Does any difference while handling normal attach and emergency attach procedures ?

Question

An LTE UE can attach to network without having any IMSI. Does there any call flow change or handling diffence w.r.t attach procedure ?

Answer 1

Go directly to the spec which describes the case.
TS 3GPP 23.401, subclause 5.3.2.1 EUTRAN Initial Attach.

Or here is a copy of it http://www.lteandbeyond.com/2012/01/lte-attach-procedure.html

Copy&Paste below:
"
For an Emergency Attach the UE shall set both the Attach Type and the Request Type to "Emergency" and the IMSI shall be included if the UE does not have a valid GUTI or a valid P-TMSI available. The IMEI shall be included when the UE has no IMSI, no valid GUTI and no valid P-TMSI.
"