The following section in RFC3551 states the same
http://tools.ietf.org/html/rfc3551#section-4.5.4
The encodings of G.726 are here denoted as G726-40, G726-32, G726-24,
and G726-16. Prior to 1990, G721 described the 32 kbit/s ADPCM
encoding, and G723 described the 40, 32, and 16 kbit/s encodings.
Thus, G726-32 designates the same algorithm as G721 in RFC 1890.
From: Brian West <brian@freeswitch.org>
To: freeswitch-users@lists.freeswitch.org
Sent: Wed, January 6, 2010 9:50:46 AM
Subject: Re: [Freeswitch-users] Codec Negotiation: Codec telephone-event:101:8000:20
They are in fact one in the same please see ITU.
/b