It is a protocol used to identify signaling encapsulation. Signaling is used to identify the state of connection between telephones or VOIP terminals ( IP telephone or PCs or VoWLAN units ). List of signaling protocols:

• QSIG
• H.225.0
• Session Initiation Protocol (SIP)
• H.323
• H.248
• MGCP
• SS7
• C7
• C5
• DTMF
• R1
• R2
• ISDN
• NBAP

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