They do not require a real time connection
It is a device which used for taking and reasoning in between two persons is called cellular telephone networks
VoIP works on telephone or cellphone connected to the internet and computer. It uses internet networks and not telephone networks.
The telephone call has been transmitted over data networks/internet.
VoIP is Voice Over Internet Protocol a telephone system that uses internet networks instead of telephone networks.
Show the formation of a T1 frame and an E1 frame used in telephone networks
how we use Public switched telephone networks to carry all our digital contents
http://wiki.answers.com/Q/How_is_the_data_and_imformation_transimited_over_public_telephone_network,public switched telephone networks and intergrated service digital networks.
0121 serves the Birmingham, England area for telephone networks.
networks
A net messaging system is a platform that allows users to send short messages to each other . This is commonly known as chatting and is available on social networks.
Telecommunication over telephone networks.
A BBM, or "Blackberry message", is a messaging app that is specific to a Blackberry. This messaging app is compatible with any other phones on any other network.