I was served with a summons by the local sheriffs dept. the summons (to a court 300+ miles away)came attached only to the service page there was no complaint/petition attached. No signature was required. Can I file an answer to the summons stating improper service and asking for a motion to dismiss?

Most summons do not require the person to sign. Where you given notice of the suit and given the court and case number. That may well be proper service, why do you feel it was not proper.

Most summons do not require the person to sign. Where you given notice of the suit and given the court and case number. That may well be proper service, why do you feel it was not proper.

The summons states clearly that "attached is the complaint/Petition" but it was not attached.
Without a complaint I cannot dispute or "answer" anything.

You will not get anything dismissed. Improper service is nothing more than a delaying tactic.

You contact the court telling them you received the summons without the complaint and ask that it be sent to you immediately and that the time frame to answer be extended.