There are many ISUP dialects, used by different hardware vendors. CISCO for example claims that they support more than 60 dialects.
This page is an attempt to give some information about the differences in the dialects. Please update this page if any additional info is available

ANSI sequence:

-> IAM
<- CPG
<- ACM
<- ANM
(Voice transfer)
<- REL
-> RLC

ITU

-> IAM
<- ACM
<- CPG
<- ANM
(Voice transfer)
<- REL
-> RLC