public void DeleteCall(Call call)
{
this.callList.Remove(call);
}
//10. Add methods in the GSM class for adding and deleting calls from the calls history.
//Add a method to clear the call history.
public void AddCall(Call call)
{
if (callList == null)
{
callList = new List<Call>();
}
this.callList.Add(call);
}