AASTRA DT4x2 for MD Evolution User Guide EN - Manual (Page 66)

Call Forwarding Services
MD Evolution – Cordless DT412 / DT422 / DT432 66
Notes:
When any type of call forward is defined on your extension,
you still have the option of placing calls and activating any
type of service from your extension.
When you have defined any type of call forward to an
internal recipient, the latter has the option of calling you
without any restrictions.
When a call forward on busy condition is defined on your
extension, no more incoming calls will be presented to you
when you have an ongoing call. In the same way, the
services of consulting and answering a new call are de-
activated.
For any call forward defined to be directed to an external
recipient, forwarding of calls issued from external parties
may take place either through your facility's resources or
directly at the ISDN network level, according to your
facility's configuration.
You may program a call forward from your extension to
itself. This enables you to bypass any fixed call forward that
is applicable to your extension. Your extension is therefore
available normally.
Serial call forwards between different users are authorized.
Your extension may also be subject to call forwarding from
third party sets. Certain extensions (such as yours) may
possibly be equipped with permanent protection against
receiving call forwards from third party sets. Obviously, this
service will be denied on these extensions (and vice versa).