I am not sure if this is possible, bearing in mind that your mobile users whilst out in the big bad world will be using the mobile provider's network to route calls - not your own. (unless you network is insanely big).
It is possible to control the cost of mobile calls when in the office however, there are products available such as installing your own private gsm base station and having the mobiles connect to this whilst on site.
There may be a cheeky workaround actually. In the UK, one of our providers (o2) offers a family bolt-on that offers free calls between configured numbers (that are o2 only). What if you installed a gsm gateway and integrated it with CUCM and Unity. Add this central gsm number to your users' bolt-on service and they can call it for free (in theory). Then configure the call routing from this gsm gateway to route to Unity and set up an auto attendant to route calls or dial by extension.
It may just work, but o2 would not like it for sure.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.