Firstly, many PhD programs have no coursework except for some few credit hours that include research methodology course and so on. In some countries, if a candidate has completed courses like Research Methodology, he just provides evidence of completion to the destination university for exemption.
If the PhD program of the university the candidate is leaving has no coursework then there is no need for transfer of credit hours. The candidate can continue with his research with the university s/he transfers to providing s/he has understanding with the new supervisor.
However, PhD programs structures differ from one university to another or from one country to another. In this case, I believe it will be difficult to transfer the credit hours obtained from the previous university unless there is semblance in the structures from university A to university B.
LEMA ALGUNO, PERO TODAS LAS UNIVERSIDADES INDUES TIENEN ESTE TIPO DE CONVENIOS, TIEBES QUE PREGUNTAR, GRACIAS, GERMAN VEGA BRIONESROB PIRTSIX EEBE DSI,NO