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ENUM alternatives
Until ENUM (or a similar standard) is widely adopted by serv-
ice providers, enterprises using SIP can leverage existing solu-
tions such as LDAP (Lightweight Directory Access Protocol)
to store both a user’s URI and all associated phone numbers
(E.164 addresses). SIP applications can then reference entries
stored in LDAP structures to resolve and translate phone
numbers to URIs.
Vendors are already expressing support for LDAP intercon-
nectivity. For example, with a simple plug-in, Avaya’s SIP
Enablement Services platform can interface with LDAP to
send calls bound for SIP URIs to standard telephones on the
enterprise’s IP PBX.
Part 4: How SIP Transforms Enterprise Communications
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SIP guide