In my view, SBC chose to assume the new name AT&T ( or at&t as you wish) because it was a brand recognized worldwide. Very few people, even those in the industry recognized "SBC". They might have recognized Southwestern Bell Telephone, but the AT&T brand was just too well known to ignore. I have worked internationally for about 12 years and most of the people I came in contact with recognized the AT&T brand. And that certainly carries weight at the International Telecommunications Union (ITU).
Regards.
Charles G. Gray Senior Lecturer, Telecommunications Oklahoma State University - Tulsa (918) 594-8433