AS11712 BELLSOUTH

BELLSOUTH is one of the surviving BellSouth autonomous systems, held today by AT&T Services, Inc. ARIN registered the ASN in November 1998 and the org record now points at AT&T's Enterprise IP Group in Indianapolis. Despite the famous name, this is not one of AT&T's big eyeball or backbone ASes.

What it's used for

The routing table is the whole story. RIS sees six IPv4 prefixes and 30,976 addresses on this AS, with two observed neighbours and no IPv6. A tier-1 carrier's transit AS peers with hundreds to thousands of networks; two neighbours means this AS is a leaf hanging off AT&T's own backbone, carrying an internal estate rather than customers or transit. The prefixes are the old BellSouth 139.76 blocks plus a pair of 72.157 /21s.

The registrant list matches: the 139.76 space is registered straight to BELLSOUTH / AT&T Services, and the two 72.157 /21s carry AT&T's internal SWIP naming (BLS-72-157-240-0-…, org "BMF BPRG Equipment BRIC - BHM" and "… CRIC - CLT"). Those are AT&T-internal equipment allocations tagged by site code, not third parties — exactly the intra-group registrant pattern that must not be mistaken for leased space.

Notable

The name is a trap worth flagging. AS11712 wears the BELLSOUTH handle, but the space behind it is a small, internally-scoped estate inside AT&T, not the consumer DSL and fibre footprint people associate with the BellSouth brand. Classifying this AS from its handle rather than its routing would put a couple of dozen thousand addresses in the wrong bucket entirely.