LG -G510 User Manual page 151

The Call divert service allows to divert incoming voice calls, fax calls,
and data calls to another number. For details, contact your service
provider.
Press [Menu] in standby mode.
Press for direct access or use
.
Diverts voice calls unconditionally.
Diverts voice calls when the phone is in progress.
Diverts voice calls when the phone is switched off or out of range.
Diverts voice calls which you do not answer.
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