[Asterisk-Users] SIP Phone -> PBX Phone

[P J]

Hi,

I'm new to Asterisk, and am researching information on linking Asterisk
to an existing PBX. Could somebody please help me with what might be
required for the following setup? -

- We have an existing PBX.
- I am going to setup Asterisk on our internal network along with some
internal SIP phones.
- I understand how Asterisk will act as the SIP Server, and SIP phones
will be able to call each other, however -

- I would also like to link Asterisk to our existing PBX so that SIP
phones could call standard phones on our existing PBX system (and
vice-versa).

- I *do not* need to use Asterisk to call out via PSTN or ITSP. All
outbound calls will be via the existing PBX.


What hardware device is required to link the Asterisk box to the
existing PBX?

Could the SIP phones call the standard phones on our existing PBX
system? If so, how does Asterisk do this?


Thanks in advance.

Ps. Even though I *do not* need to use Asterisk to call out via PSTN,
what hardware device would be required to do this? And, how does this
device differ from the device that links Asterisk to the existing PBX?