[Trish]

According to the CA civil code:

116.740. (a) If the defendant was not properly served as required
by Section 116.330 or 116.340 and did not appear at the hearing in
the small claims court, the defendant may file a motion to vacate the
judgment with the clerk of the small claims court. The motion shall
be accompanied by a supporting declaration, and shall be filed
within 180 days after the defendant discovers or should have
discovered that judgment was entered against the defendant.
(b) The court may order that the enforcement of the judgment shall
be suspended pending a hearing and determination of the motion to
vacate the judgment.
(c) Upon a showing of good cause, the court may grant the motion
to vacate the judgment. If the plaintiff is not present, the court
shall hear the motion in the plaintiff's absence.
(d) Subdivisions (d), (e), and (f) of Section 116.730 apply to any
motion to vacate a judgment.

This is only a small section of it though...... you should look through it:
CALIFORNIA CODE OF CIVIL PROCEDURE


ETA: regarding the process server laws, read here:
California Rules of Civil Procedure, Process Serving Laws ? ServeNow.com

To me (and this is just my interpretation - you may want to contact a process server and ask them) a neighbor would not be sufficient....looks like it needs to be a member of the household..

u00a7 415.20

1. In lieu of personal delivery of a copy of the summons and of the complaint to the person to be served as specified in Section 416.10, 416.20, 416. 30, 416.40, or 416.50, a summons may be served by leaving a copy of the summons and of the complaint during usual office hours in his or her office with the person who is apparently in charge thereof, and by thereafter mailing a copy of the summons and of the complaint (by first-class mail, postage prepaid) to the person to be served at the place where a copy of the summons and of the complaint were left. Service of a summons in this manner is deemed complete on the 10th day after such mailing.
2. If a copy of the summons and of the complaint cannot with reasonable diligence be personally delivered to the person to be served as specified in Section 416.60, 416.70, 416.80, or 416.90, a summons may be served by leaving a copy of the summons and of the complaint at such person’s dwelling house, usual place of abode, usual place of business, or usual mailing address other than a United States Postal Service post office box, in the presence of a competent member of the household or a person apparently in charge of his or her office, place of business, or usual mailing address other than a United States Postal Service post office box, at least 18 years of age, who shall be informed of the contents thereof, and by thereafter mailing a copy of the summons and of the complaint (by first-class mail, postage prepaid) to the person to be served at the place where a copy of the summons and of the complaint were left. Service of a summons in this manner is deemed complete on the 10th day after the mailing. (Amended by Stats. 1989, Ch. 1416, Sec. 15.)