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In the small and medium business market, legacy TDM-based PBXs are often configured with shared call appearance lines for incoming calls. Shared call appearance lines are lines that appear on multiple phones and deliver the following functionality:
Caution - BLA does not work properly with Polycom 4.1.8 and higher firmware loads on VVX phones and Polycom 4.0.6 and higher on Soundpoint IP phones. A 'ghost' line with red light appears on the phone answering the BLA-enabled line. This issue was resolved with Polycom 5.2.5 firmware on VVX Business Media Phones and verified with Sipxcom release 15.10. Polycom has not yet applied 'ghost line' fix for the Soundpoint IP phones - this issue continues to appear for every firmware release starting with Polycom 4.0.6 and higher.
Step 3 - Assign the Lines to the Phones
Assign the personal line as the first line on each phone, and the BLA-enabled main line as the second line. For the BLA-enabled line on each phone, go to the Line->Registration section, and change the number of line keys on each phone to 3 from 1, and the Calls Per lLine Key from 24 to 1. This step is necessary for creating the roll-over effect on the main line.
Step 4 - Between sipXcom 14.10 and 18.12, Provision SIP Domain Name in the Registration Outbound Proxy Field
From release 14.10 and 18.12, the SIP domain name of the sipXcom server is not automatically provisioned in the Outbound Proxy field in the Phone->Line->Registration menu - this has been corrected in release 19.04. Go to the Phone->Line->Registration menu for each phone where there is a shared line defined, and provision the Phone->Line->Registration menu field with the SIP Domain Name of the voice server.
Step 5 - Disable Alert-Info For External Calls
Go to the System->Six Proxy>Sipxproxy menu and disable the Enable for external calls Alert-Info options. This capability is normally used to map calls to specific call waiting types and (beep, ring, and silent) - Sipxproxy inserts Alert-info values and class fields in the SIP header when this option is enabled that informs the phones what ring types are used. With BLA lines and the Enable for External Calls Alert-Info option disabled, Sipxproxy will check each appearance of a BLA-enabled line on the phone whether it is available to handle an incoming call. With the Alert-info option enabled, Sipxproxy will not check each appearance of a BLA-enabled line on the phone. With the CallsperLineKey option set to 1, Sipxproxy will send subsequent calls to voicemail or the AA when the first main line is active and Alert-Info options are enabled.
6 - If Using sipXcom 14.10 and Higher with BLA, Change Firewall Settings for the SAA/BLA Services
This step is required when using sipXcom release 14.10 and higher with the BLA feature enabled. The issue has been pinpointed to default SIP server IP address not being passed to the phones. Go to the System->Firewall->Rules menu, and change the firewall settings for the SAA/BLA TCP and UDP services from CLUSTER to PUBLIC. Bridged Line Appearance services works for both standalone and high availability configurations. This issue has been corrected in sipXcom 18.12.
7 - Suggested Options When Main Line Incoming Call is not Answered
When using BLA on the main line, a suggested best practice is to place the main in a hunt group - this provides the greatest flexibility for implementing three options.