Short answer. It depends how you appear. A defendant's voluntary appearance is equivalent to service of summons, curing any defect in service. But including grounds other than lack of jurisdiction over your person in a motion to dismiss is itself treated as a voluntary appearance, which can waive the objection you meant to raise.
What the law says
The defendant's voluntary appearance in the action shall be equivalent to service of summons. The inclusion in a motion to dismiss of other grounds aside from lack of jurisdiction over the person of the defendant shall be deemed a voluntary appearance.
Rule 14, Section 23 — Voluntary appearance. Read the full provision →
Voluntary appearance substitutes for proper service
The rule states plainly that the defendant's voluntary appearance in the action shall be equivalent to service of summons. Whatever defects existed in how summons was actually served, or even if it was never validly served at all, the defendant's own voluntary appearance accomplishes the same jurisdictional purpose that proper service was meant to achieve, effectively curing the defect.
Mixing grounds in a motion to dismiss can backfire
This is the trap in the rule: the inclusion in a motion to dismiss of other grounds aside from lack of jurisdiction over the person of the defendant shall be deemed a voluntary appearance. A defendant who wants to preserve an objection to defective service has to raise that objection carefully — combining it with unrelated grounds for dismissal in the same motion can itself be treated as submitting to the court's jurisdiction.
This is a real, easy-to-miss trap: it is not the court's ruling that creates the voluntary appearance, but the defendant's own act of raising other grounds alongside the jurisdictional one in the same filing.
Why this distinction matters in practice
A defendant who believes summons was never validly served has a real interest in challenging the court's jurisdiction over them before doing anything else that could be read as accepting it. Filing a motion to dismiss on the ground of lack of jurisdiction over the person, without folding in other unrelated grounds, is what keeps that specific objection from being deemed abandoned by the defendant's own appearance.
The stakes of getting this wrong
If defective service is genuinely the defendant's strongest defense, mishandling the motion to dismiss by combining it with other grounds can waive that defense entirely — the case then proceeds as though summons had been properly served all along. Anyone in this position should be precise about which grounds they raise, and in what combination, before filing anything with the court, ideally with counsel who understands this particular trap.