[Jeffry]

Code:

CellPhone[CellPhone[playerid][CalledBy]][InCall]= -1; 
SendClientMessage(CellPhone[playerid][CalledBy], COLOR_GREY, "Line went dead..."); 
CellPhone[CellPhone[playerid][CalledBy]][CalledBy] = -1;

to:

Code:

if(CellPhone[playerid][CalledBy] != -1)
{
	CellPhone[CellPhone[playerid][CalledBy]][InCall]= -1; 
	SendClientMessage(CellPhone[playerid][CalledBy], COLOR_GREY, "Line went dead..."); 
	CellPhone[CellPhone[playerid][CalledBy]][CalledBy] = -1;
}