Overview:
    We were asked to use out current Digital (not-IP) Avaya Audix system to carry the numbers of a few on-site employees to an new rented office building.  The short answer is that it could not be done for free and without having control over the phone systems at the remote location.  The solution we were left with was to forward the calls off site using coverage paths in Audix.  This solution is not ideal but this post describes how forwarding calls off-site is done and provides reasons you can use to convince executives that the solution should be scraped.

First a few definitions:

Coverage Paths, Coverage Points, Remote Coverage & Hunt Groups
Coverage paths (cmd: list coverage path)
    The only major function is to redirect a call from an extension to another extension, path, hunt group, or remote number.  A coverage path can have an     adjustable number of rings.
Coverage point:  (Point 1: ____  within a coverage path)
    Coverage points the targets of a coverage path.  All remote numbers, hunt groups, and other coverage paths can act as coverage points.  If you want coverage path 3 to transfer its calls to Coverage path 2 then under Point 1 you type c2.  For Hunt group 71 you put h71 and for the remote coverage number in     slot 53 you put r53.
Hunt groups (cmd: list hunt-group):
    Hunt groups are multi extension targets like group sales number.  They can have     adjustable behavior but in general they allow for the number to hit multiple lines     at once or they can choose an extension at random to forward the call to. Hunt Group 99 is Audix Voice mail.
Remote Coverage Numbers (cmd: change coverage remote):
    The Remote Coverage table contains the numbers of off network phones that     can be used as the targets of coverage paths.  The numbers in this list need to be     input the exact same way as they would be on the phone.  Thus my cell phone     number looks like 6095558561  If you use a coverage path to forward a call to     a remote number that call cannot be returned to audix voice mail.

Forwarding a Call off site.
So at this point forwarding a call to an out of system phone is as simple as creating one new Coverage Path and having its end point be a Remote Coverage Point.

Coporate Drawbacks
   1.   Calls that are forwarded to off site numbers can not be returned to the in-house voice mail.
   2.   You can not mask calls from the off site numbers.
   3.    Every call counts as 3.  You are charged for the incoming phone call. You are charged for making the call that forwards it to the      off-site number and you are charged by who ever is providing your phone service at the off-site location.

Conclusion:
This attempt to spare the off-site employees the inconvenience of updating their contact information is so flawed it should not be attempted.  I good compromise is to set up this type of forwarding for the 1st month after relocation to assist the employees in their transition but a permanent solution is either an update to an IP phone system or setting up another digital switch at the off-site office.