Folks,
I just recently discovered that the ITU-T published a
corrigendum to T.38 (1998) that apparently breaks backward compatibility for
all T.38 devices currently deployed that follow the original 1998
specifications. The particular document in question is Corrigendum 1,
which was approved in 2000 and subsequently published in May 2001. You
can download the corrigendum document for free from this
site:
http://www.itu.int/rec/recommendation.asp?type=folders&lang=e&parent=T-REC-T.38
The issue at hand is a change in the ASN.1 syntax
found in Annex A/T.38. The particular data structure is shown
here:
Data-Field ::= SEQUENCE OF SEQUENCE
{
field-type ENUMERATED
{
hdlc-data,
hdlc-sig-end,
hdlc-fcs-OK,
hdlc-fcs-BAD,
hdlc-fcs-OK-sig-end,
hdlc-fcs-BAD-sig-end,
t4-non-ecm-data,
t4-non-ecm-sig-end,
...
},
field-data OCTET
STRING (SIZE(1..65535)) OPTIONAL
}
The syntactical change was the addition of an
ellipsis at the end of the ENUMERATED "field-type". In the published
1998 specification, this ellipsis did not exist.
What I would like to know is whether this
change impacts your product or not. I am aware of many deployed
devices on the market today that employs the 1998 syntax without this
ellipsis. I would like to find out to what extent this change is going
to present problems for companies represented on various
lists and, if I get sufficient support, I want to take a contribution to the
ITU-T SG16 meeting in May to try to resolve this problem in such a way as to
not break backward compatibility and interoperability.
I am looking forward to your
replies.
Kindest Regards,
Paul E.
Jones