I am PhD student on F1 visa, currently in India pursuing my research. I need to extend my trip for longer than a year for more research. However, the office of international students (OIS) at my University tells me that according to some federal policy, I must make a trip back to the US within 1 year or I might get into trouble at the port of entry. They have not directed me to this policy though.I know of other PhD students on F1 VISA who stayed outside of the US for research for more than 1 year and had no trouble going back, nor did their Universities warn them about this. I called ICE, and they told me that staying for more that 1 year on research should be fine as long as I continue to be a registered student and my i20 has updated travel signature.I am certain that I will be a full time registered student through this period and am planning to renew the travel stamp on my i20 by mail. The OIS says they will renew the i20 stamp but still strongly advise to make a trip to the US within a year. Please advice.