Yealink SIP-T21 E2 User Manual page 136

User Guide for the SIP-T21(P) E2 IP Phone
The default value is 1. In this example, the value is set to 2.
4. Click Confirm to accept the change.
The phone A will automatically configure the line keys from the first unused DSS key,
according to the configured number in the Number of line key field.
To configure the shared line settings and the number of line key on phone B via web
user interface:
1. Register the alternate account 4603_1.
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