Administrator’s Guide for SIP-T2 Series/T4 Series/T5 Series/CP920 IP Phones
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The difference between Shared Call Appearance (SCA) and Bridge Lines
Appearance (BLA)
SCA and BLA are similar signaling methods that enable more than one phone to share a SIP line. The method you use
varies with the SIP server you are using. In the configuration files, the relevant configuration parameters of SCA and
BLA are different. The barge-in and call pull feature are not available with BLA; but they are available with SCA.