For customers using the divert facility on a Centrex extension, there are now 3 divert modes available with slightly different behaviour.
Delayed Parallel:
This is the original Centrex style of divert, which works by
calling the SIP phone in parallel with a delayed divert. In
other words, your SIP phone will ring, and after the specified
delay, your divert number will be called, and your SIP phone
will keep ringing.
This is a very useful style of divert if your SIP phone is
always online. Unfortunately if your SIP phone is not always
online, or unavailable for some other reason (e.g. the line is
busy with another call) then the caller will hear silence until
the delay period has elapsed and the divert number starts
ringing.
Sequential:
This is much more like a 'standard' divert. The SIP phone is
called, and if it either fails (offline, busy, etc) OR is not
answered within the divert delay, the call is cancelled and the
divert number is called instead.
This has the advantage of being much more 'user friendly' in the
case of the SIP phone being offline, but does mean that when
the divert activates, the SIP phone will STOP ringing. If you
have a short divert time, and like to be able to pick up on your
SIP phone even after the divert has started, this option will
not work for you.
Sequential with repeat:
This is a sort of hybrid of the above methods. It is the same
as sequential, but after the SIP phone either times out or
fails, the divert AND the SIP phone again will be called in
parallel.
This does however mean that two seperate calls are placed to the
SIP phone - so if for example you miss the call and pick it up
on your divert number, your SIP phone will register two missed
calls instead of phone.
All three divert modes have their pros and cons, and we recommend you experiment with them to find the one that suits you best.