Yealink SIP-T29G User Manual page 221

To register an account and configure BLA feature on phone B via web user interface:
Register the account 10462190020.
1.
Click on Advanced, and then select Draft BLA from the pull-down list of Shared Line.
2.
Enter the desired number in the BLA Number field.
3.
Click Confirm to accept the change.
4.
Advanced Phone Features
209