Short answer. Yes, but only with the court's permission. If the defendant's identity or whereabouts are unknown despite diligent inquiry, the Rules of Court allow service by publication in a newspaper of general circulation, once the court grants leave and sets the terms.
What the law says
whenever his or her whereabouts are unknown and cannot be ascertained by diligent inquiry, within ninety calendar days from the commencement of the action, service may, by leave of court, be effected upon him or her by publication in a newspaper of general circulation and in such places and for such time as the court may order
Rule 14, Section 16 — Service upon defendant whose identity or whereabouts are unknown. Read the full provision →
This is a last resort, not an automatic option
Service by publication is available only where the defendant's whereabouts are unknown and cannot be ascertained by diligent inquiry — the plaintiff has to have actually tried, and failed, to locate and personally serve the defendant before this route opens up. It also requires leave of court: the plaintiff cannot simply publish a notice and treat the defendant as served; the court must first authorize it. Skipping the diligent-inquiry step, or serving by publication without leave, does not satisfy the rule.
The court sets the terms of publication
Once leave is granted, the court decides the newspaper, the places, and the length of time the publication must run — these are not left to the plaintiff's choice. The rule requires a newspaper of general circulation, and the court's order will specify exactly how the publication is to be carried out so that it gives the defendant a real, if imperfect, chance of learning about the case.
The defendant still gets time to answer
The court's order granting leave to serve by publication must give the defendant a reasonable period to answer, which cannot be less than sixty calendar days after notice. This is longer than the answer period in an ordinary case, reflecting how much less certain it is that a defendant served this way has actually seen the summons. The court, not the plaintiff, fixes the exact length within that floor, based on what it considers reasonable for the case.
There is a window for requesting this
The rule ties this remedy to the timing of the case itself, allowing it within ninety calendar days from the commencement of the action. A plaintiff who has exhausted efforts to find the defendant should raise the possibility of service by publication with the court promptly rather than letting the case stall indefinitely for lack of a locatable defendant. Waiting past that window can leave a plaintiff without this particular avenue for reaching an untraceable defendant.