Correct communication tool is dependent on the situation it is used. If we have to communicate something very urgently, it is always better to give a call. But if it is to document something and to be used for the future reference, we will have to go for an email. If somebody use these methods other way around what would be the effect. Obviously your lead time will go high.
Using inappropriate methods in information exchange, will lead to overloading of information and waiting for information. This can lead to wrong information creation in the system. It is needless to say how complicated your system would be in these scenarios.