Cisco TelePresence Administrator's Manual page 87

Protocols
accept registration requests for any SIP endpoints attempting to register with an alias that includes these
domains.
The domain name can comprise multiple levels. Each level's name can only contain letters, digits and
hyphens, with each level separated by a period (dot). A level name cannot start or end with a hyphen, and the
final level name must start with a letter. An example valid domain name is 100.example-name.com.
Note that values shown in the Index column correspond to the numeric elements of the %localdomain1%,
%localdomain2%, . . . %localdomain200% pattern matching variables.
You can configure up to 200 SIP domains.
Cisco VCS Administrator Guide (X7.2) Page 87 of 498