This is my scenario. Please Help

I’m very new at this so any help would be great.

I have a small office with 2 ISDN lines coming in
I want to setup asterisk and have my secretary transfer incoming calls to sales reps, tech support etc.

-Is that possible with asterisk?
-what type of hardware do I need to connect 4 external lines and have lets say 8 or 10 internal extentions (I dont mind using sip)?
-Is it possible to have the secretary pick up the phone from her home (she has DSL and her pc is allways on) and transfer the line to the office?

thats it for now.
Please help me.
Thanks in advance.

I am new to this as well but
Yes to all of the questions.
you need a ISDN card for incomming lines. look at Digium.com
You can use VoIP phones for all internal lines.
As far as getting internet based calling to work, this has been quite a problem for me so far. I am not having much success with freeworlddialup (fwdnet.net) and iaxnet.net , the two services that let you do phone to phone/Asterisk calling.
James

For your secretary: Is she connected via a VPN or are you going to open ports in your firewall for the traffic to go in and out of… Something to consider…

It would be very easy to direct all incoming traffic to your secretary… In either scenario above - And then your secretary could transfer traffic where ever needed.

You could also direct all calls into a phone tree - very easy to setup as well. Then the secretary could answer any calls sent to 0, the operator…

Hardware:

Look at ebay for the following:

Dell Poweredge 2550 ~ $650, way overkill for your size but is a nice server
SIP compatible phones ~ $800-3000, depending on model
X10 phone for secretary ~ $60
Headset and boom for secretary to plug into sound and mic on pc ~ $20
ISDN card from Digium, you will have to lookup, probably ~ $300 guess

Assuming you allready have some sort of telephones in your office. Use the phones you allready got. Plain and simpel.
Get ATA’s (Analog Telephone Adapters), and then your ol’ phones work. No need to spend money on fancy pancy special VoIP telephones. Because you set things up in asterisk, like forwarding, voicemail, conference call etc. These are all asterisk features.

So let asterisk handle what asterisk does best, and stick to your old handset. And save money while doing so.

For the rest of the HW see the other answers.