EM interface

EM interface the hardware interface with common switching equipment of a kind of phone.

EM interface is interface of a kind of imitate, its information and continue letter make be departure. Cent is second line EM and 4 lines EM two kinds. The same way that send signal, identical letter must be used when undertaking EM butt joint your interface means. And E line and butt joint of line of M of the other side.