You must dial 91 to get an outside line on this system [example +91 610 667 7822]
You must dial 9011 to call internationally [example +9011 33 1 49 27 01 79]
Unplugging your phone from power and plugging it back in will resolve most connectivity issues.
In the event you need dial 911, you do NOT need include 91. Simply dial 911 and you will be connected to emergency services.
Refer to http://insigniamextensions.com for a quick convenient list of Insigniam's extension list.
See a list of all the useful guides and practices for phones here on the Insigniam Support site.
Deskphone Wireless Headset Reference