Hey, it's your Ninja
There's more than just a standard GSM network powering the Ninja Tel network. Ninja Tel uses a little-known feature of Android 4.0 Ice Cream Sandwich that allows networks to route calls over GSM or onto Wi-Fi, if the Wi-Fi has been configured properly using Session Initialization Protocol (SIP) and has a SIP Server.
July 28, 2012 5:44 PM PDT
Photo by: Seth Rosenblatt/CNET
| Caption by: Seth Rosenblatt
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