Connecting two standard editions of Skype fo Business 2015

Hi moorec43,

if those domains are separate ad forests you have to use the edge server role to connect them. Pairing the standard editions is only possible if they share the same ad forest.
Supported AD topologies can be found here:
https://docs.microsoft.com/en-us/SkypeForBusiness/plan-your-deployment/requirements-for-your-environment/environmental-requirements#ad-topologies
This edge server is sitting in the DMZ and allows connectivity for all SfB workloads between the two deployments.
You can have a look at the reference typologies to get idea how this looks:
https://docs.microsoft.com/en-us/skypeforbusiness/plan-your-deployment/topology-basics/reference-topologies

Depending on the network environment this setup can be challenging. If you do not have a shared network infrastructure and have different DMZ it is good starting point.

A point to start planning for the edge deployment can be found here:
https://docs.microsoft.com/en-us/SkypeForBusiness/plan-your-deployment/edge-server-deployments/edge-server-deployments

There are also a few blog posts out there how to deploy the edge role. This is an example from Jeff Schertz:
http://blog.schertz.name/2016/03/skype-for-business-2015-edge-server-deployment/

Paul