* @desc Establish a call. This function waits for a call incoming event and accepts the call. An optional message box is displayed if msg is not empty.
* @param msg optional message to display before waiting for incoming call, if the message is an empty charstring no message box is displayed
* @param p_establishMessage Optional message to display before waiting for incoming call, if the message is an empty charstring no message box is displayed
* @desc The time elapsed time between <code>first</code> and <code>second</code> in milliseconds. The format of the timestamp is assumed to be <code>yyyy-MM-dd'T'HH:mm:ss.SSS</code>.
* @desc Return a <code>charstring</code> containing onliy the time from the given timestamp. The format of the timestamp is assumed to be <code>yyyy-MM-dd'T'HH:mm:ss.SSS</code>
*
* @param ts timestamp to extract time from
* @param p_ts Timestamp to extract time from
* @return Time in the format <code>HH:mm:ss.SSS</code>