Aastra M401 User Manual page 19

You now have the same options as when you call a second party while you're already
connected to a first call (see 2.2. to 2.5.).
1. To return to your first caller and disconnect your second caller
Press the key
then
Press the key
2. To "shuttle" between the first call and the second call
Press the key
then
Press the key
3. For a three-party conference call
Press the key
then
Press the key
Receiving one
or more calls
R
1
R
2
R
3
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