Yealink SIP-T54S Administrator's Manual page 690

Administrator's Guide for SIP-T2 Series/T19(P) E2/T4 Series/T5 Series/CP860/CP920 IP Phones
depends on support from a SIP server.
Any IP phone can be used to originate or receive calls on the bridge line. An incoming call to
the BLA number can be presented to multiple phones in the group simultaneously. The
incoming call can be answered on any IP phone of the group but not all.
IP phones support BLA using a SUBSCRIBE/NOTIFY mechanism as specified in
event used is:
"dialog" for bridged line appearance subscribe and notify

If the call is placed on public hold, the held call is available for all phones in the group to
retrieve.
Procedure
BLA can be configured using the following methods.
Central Provisioning
(Configuration File)
Web User Interface
Details of Configuration Parameters:
account.X.shared_line
Description:
Configures the registration line type for account X.
664
<MAC>.cfg
Parameters
Configure the registration line type.
Parameter:
account.X.shared_line
Configure the BLA number.
Parameter:
account.X.bla_number
Configure the period of BLA
subscription.
Parameter:
account.X.bla_subscribe_period
Configure the registration line type.
Configure the BLA number.
Configure the period of BLA
subscription.
Navigate to:
http://<phoneIPAddress>/servlet?
p=account-adv&q=load&acc=0
Permitted Values
0, 1 or 3
RFC 3265. The
Default
0