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  • Setting Up Bridge Line Appearance Lines for Small and Medium Businesses
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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:

  • When an incoming call is mapped to a share called appearance line, the lines ring simultaneously on multiple phones.
  • When the call is answered by one phone, the status light on the answered phone goes green while the shared call appearance lines on the other phones goes red, signifying that the line has been answered by one phone.
  • If the caller is placed on hold, all the shared call appearance lines flash red, indicating that the caller has been placed on hold.
  • Any phone with shared call appearance line can take an 'on-hold' caller off of hold and make the call active again.
  • When the call is completed and the line is placed 'on-hold', the status light for a shared call appearance line across all phones is turned off.

Small and medium businesses using shared call appearance on their their existing TDM-based phone systems often request this capability when upgrading to a new phone system. Many medical, legal, and financial practices with one or more receptionists leverage the shared call appearance capability in their phone systems to answer calls centrally, and simplify the process of transferring calls from the reception area  by placing the caller on hold and requesting another person to 'pick up the line on hold'.

With sipXcom, this capability is called Bridged Line Appearance (BLA) - the remainder of this document describes how to enable this feature with Polycom VVX Business Media and Polycom Soundpoint IP phones. sipXcom releases 14.04 and 14.10 have been used to validate BLA functionality in the following lab configuration:

Each phone has three appearances of a BLA-enabled 'Main Line' x300 on their phones. Incoming calls to the main line will ring the first available main line as follows:

  • If all main lines are available, then sipXcom will ring the first appearance of x300.
  • If main line 1 is busy, the sipXcom will ring the second appearance of x300. If main lines 1 and 2 are busy, then sipXcom will ring the third appearance of x300.
  • If main line 1 and / or main line 2 lines become available and a new incoming call arrives, sipXcom will ring the first available appearance of x300.
  • If all main lines are busy and a fourth incoming call comes in, then sipXcom can be configured to either return a busy signal, go to voicemail, or trigger an auto-attendant.

(warning) The 'rollover' main line behavior only works properly when the same number of BLA-enabled lines appears on each phone. BLA lights will not appear in all cases when there is an asymmetrical number of BLA-enabled line appearances across the phones.

Step 1 - Define x300 and Enable Bridged Line Appearance

After x300 has been defined, go to Users->Phone section and click on the Shared button - this enables the BLA capability on the line.

Step 2 - Load the Polycom Firmware onto the sipXcom Voice Server

Load the Polycom Firmware and Updater onto the sipXcom voice server. Assign each device file to the correct version (4.0.x or 4.1.7). Map the phones to the correct firmware versions in the Phones->Mac Address–>Firmware Version field - push the phone profiles.

(warning) 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->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.

Step 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.

Step 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.

  1. Busy - no answer response
  2. Send the call to x300 voicemail
  3. Send the call to an auto-attendant

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  1. Great doc, thx Peter.