In my previous post I talked about options for routing calls within gateways. In this post, we’ll take a look at how Skype for Business routing options work with the gateway.

When you’re working with analog devices, you have two ways of configuring routing in SfB. The first is the standard SfB routing, which is flexible and resilient. However, analog devices don’t require this flexibility – they are attached to just one gateway by a pair of copper wires. It’s possible to simplify the routing to analog devices by the use of CsAnalogDevices, which is a SfB object you create with the New-CsAnalogDevice PowerShell command. A CsAnalogDevice object registers to a pool, allows a SIP address and display name for an object to be added to contact lists, specifies the gateway that the device is plugged in to, and offers fax handling.

When you place a call to a CsAnalogDevice, the SfB routing process will route the call to the specified gateway, and not via the normal SfB routing process. This helps keep your routing configuration tidy if you have a number of analog devices, since you would need to specify routes manually for each number. You’re entering that same information when you use CsAnalogDevice, just in a much nicer format. If you’re in a large organization, you can also use Role Based Access to allow helpdesk admins to create CsAnalogDevices, but you probably wouldn’t want to turn them loose with making routing changes in SfB.

When you place a call from the analog device, the call is handled via SfB. This means that you can also now easily apply Voice Policies to your analog devices, leveraging the configuration that you’ve already built. Without CsAnalogDevices, you would have to build out your policy manually on each gateway.

When you configure a fax as a CsAnalogDevice, you need to specify “-AnalogFax $True”. This causes SfB to route the call differently, so that the fax call is sent back to the gateway that it came from, instead of routing through SfB.

I recommend this excellent blog post on Lync Faxing. Don’t worry, nothing has changed from Lync to SfB with regard to faxes.

While I’m sending you off to other Blogs, be sure to check out Greig’s post on M:N Routing and CsAnalogDevices. Greig explains a gotcha with naming your trunks and gateways in Topology Builder that may interfere with calls when using CsAnalogDevices.

Routing is an interesting topic of its own, however you can’t really consider much about routing without also considering number translation and normalization, which is the topic of my next post.