This icon means that if you have mobile data usage enabled, the network behind the data usage is using LTE services, more importantly VoLTE (Voice Over LTE). It is basically using 4G to make voice communications, similar to what VoIP (voice over IP) is. So far this technology is being tested by most cell phone carriers, but it is already implemented by few of them.
The Symbian cell phones come in two varieties, Series 60 and Series 80. They are manufactured mainly by Nokia, and the Series 60 phones include the Nokia 3650, 3660, and 6620, which were evaluated in the November 2003, July 2004, and November 2004 issues of AccessWorld, respectively. Other Series 60 phones that we have not evaluated include the Nokia 3600, 3620, 6600, 6630, 6670, 7610, 7650 N Gage, N Gage QD, and the Siemens SX1. The Series 80 phones, which are large personal digital assistant- (PDA) style phones with full QWERTY keyboards, include the Nokia 9210, 9210i, and 9290 Communicator that we evaluated in the January 2004 issue of AccessWorld. After examining several of these phones, we recommend the Series 60 phones over the Series 80 phones because they are much smaller and more portable and come with as much, if not more, functionality. In addition, the Series 80 phones seem to be disappearing from the market, since we were not able to find any service providers in the United States that still carried them.