Glossary

P

PDU

Protocol data units used by bridges to transfer connectivity information.

POTS

Plain old telephone service. Basic telephone service supplying standard single line telephones, telephone lines, and access to the PSTN.

Proxy Server

An intermediary program that acts as both a server and a client for the purpose of making requests on behalf of other clients. Requests are serviced internally or by passing them on, possibly after translation, to other servers. A proxy interprets, and, if necessary, rewrites a request message before forwarding it.

PSTN

Public switched telephone network. PSTN refers to the local telephone company.

R

Redirect Server

A redirect server is a server that accepts a SIP request, maps the address into zero or more new addresses and returns these addresses to the client. It does not initiate its own SIP request nor accept calls.

Registrar

A registrar is a server that accepts REGISTER requests. A registrar is typically co-located with a proxy or redirect server and MAY offer location services.

RAS

Registration, admission, and status protocol. This is the protocol that is used between endpoints and the gatekeeper to perform management functions.

RBS

Robbed bit signaling.

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Cisco Systems IP phone 7960 manual Robbed bit signaling