Last week I discussed how to connect Asterisk with OCS Mediation Server over TCP.  I figured since we can connect Asterisk to OCS, why not to Exchange UM.  I will go over the configuration changes I made to Asterisk for this, but will not go into detail – since most of it was covered last week.

** Just wanted to add a side note.  This configuration is not supported, but again I like to play – so here you go. **

Asterisk Configuration Changes

SIP.CONF

[general]

context = default

bindport = 5060

bindaddr = 0.0.0.0

tcpbindaddr = 0.0.0.0

tcpenable = yes

promiscredir = yes  ** This is new line added **

promiscredir -> If set to yes, allows 302 or REDIR to non-local SIP Address

[SIP_VM]

type = peer

host = 10.100.16.20

qualify = yes

transport = tcp

[50012]

type = friend

callerid = Exchange User <50012>

secret = 50012

host = dynamic

canreinvite = no

dtmfmode = rfc2833

mailbox = 50012

disallow = all

allow = ulaw

transport = udp

You have seen most of this configuration before.  We created a new Trunk/Peer that will connect to the Exchange UM Server.  I also created a new Extension since I setup my Exchange DialPlan to support 5-Digit extensions.

Now we have to make some changes to the Asterisk Dialplan.  There are two different configurations.

1.  If you are going to call into Exchange UM.

;Exch VM

exten => 79999,1,Answer

exten => 79999,n,Dial(SIP/SIP_VM/${EXTEN})

exten => 79999,n,Busy

This just gets added to the outbound context in your dialplan.

2.  Here we will create a simple Macro to dial the extension then redirect to Exchange UM if no one answers.

; User Extension Macro

[macro-stdexten]

exten => s,1,Answer

exten => s,n,Set(MBEXT=${ARG1})

exten => s,n,Dial(SIP/${ARG1},20)

exten => s,n,SipAddHeader(Diversion:<tel:${MBEXT}>)

exten => s,n,Dial(SIP/SIP_VM/${EXCHUM})

exten => s,n,Busy

exten => _5XXXX,1,Macro(stdexten,${EXTEN})

So your extension.conf file will now look like this:

[general]

static=yes

writeprotect=no

[globals]

EXCHUM = 79999

[default]

exten => _5XXXX,1,Macro(stdexten,${EXTEN})

include => outbound

[macro-stdexten]

exten => s,1,Answer

exten => s,n,Set(MBEXT=${ARG1})

exten => s,n,Dial(SIP/${ARG1},20)

exten => s,n,SipAddHeader(Diversion:<tel:${MBEXT}>)

exten => s,n,Dial(SIP/SIP_VM/${EXCHUM})

exten => s,n,Busy

[outbound]

exten => _NXXNXXXXXX,1,Set(EXT=+${EXTEN})

exten => _NXXNXXXXXX,n,Dial(SIP/SIP_TRUNK/${EXT})

exten => _NXXNXXXXXX,n,Busy

;Exch VM

exten => 79999,1,Answer

exten => 79999,n,Dial(SIP/SIP_VM/${EXTEN})

exten => 79999,n,Busy

Now this is done we will move onto the Exchange UM configurations.

The first step is to create a UM Dial Plan.  Open up Exchange Management Console -> Under Organization Configuration -> Unified Message.  Select New UM Dial Plan.  There will be a wizard that walks you thru the configuration.  The important pieces are: 

-    URI Type: Telephone Extension

-    VoIP Security: Unsecured

Once you have the Dial Plan configured -> edit the dial plan and create a Subscriber Access Number.

I’ve personally been waiting for this release of Asterisk for some time now! After researching a little, I found out that Asterisk 1.6 now supports TCP & TLS.  Currently it is still considered experimental – but hey, it’s always fun to play!

For those of you who are only familiar with Trixbox or FreePBX, there is no support for any graphical interface on 1.6 as of yet.  But,I will keep this simple and to the point.  Installing Asterisk on a Linux box with Kernel 2.6 is fairly straightforward.  In this Lab, I deployed CentOS 5 - Kernel 2.6.18 with Asterisk 1.6.  When installing the OS you will also need the Kernel Sources and Kernel Headers packages.

First step of course is to build a Linux Box – I built mine in a VM, but installing on hardware will work just the same. 

You can download Asterisk from www.asterisk.org. On your Linux box make a directory under /usr/src – called pbx.  From that directory you can use the following command: