Aastra M401 User Manual page 17

2.5 TRANSFERRING CALLS
If you wish to connect the first party with the second party:
Replace your handset
Both parties are connected with one another, without you on the line.
Please note:
Transfer is not always possible between two external numbers. If the transfer is unsuccessful,
your phone will ring after you have hung up. The parties will remain on line.
Calling a second party
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