No, you do not need to call back.  You can't be "served" via phone, fax or email - that's just ridiculous!  Please read the following:

Consumers across the country report that they're getting telephone calls from people trying to collect on loans the consumers never received or on loans they did receive but for amounts they do not owe. Others are receiving calls from people seeking to recover on loans consumers received but where the creditors never authorized the callers to collect for them. So what's the story?

The Federal Trade Commission (FTC), the nation's consumer protection agency, is warning consumers to be on the alert for scam artists posing as debt collectors. It may be hard to tell the difference between a legitimate debt collector and a fake one. Sometimes a fake collector may even have some of your personal information, like a bank account number. A caller may be a fake debt collector if he:

is seeking payment on a debt for a loan you do not recognize;
refuses to give you a mailing address or phone number;
asks you for personal financial or sensitive information; or
exerts high pressure to try to scare you into paying, such as threatening to have you arrested or to report you to a law enforcement agency.
If you think that a caller may be a fake debt collector:
Ask the caller for his name, company, street address, and telephone number. Tell the caller that you refuse to discuss any debt until you get a written "validation notice." The notice must include the amount of the debt, the name of the creditor you owe, and your rights under the federal Fair Debt Collection Practices Act.
If a caller refuses to give you all of this information, do not pay! Paying a fake debt collector will not always make them go away. They may make up another debt to try to get more money from you.

Stop speaking with the caller. If you have the caller's address, send a letter demanding that the caller stop contacting you, and keep a copy for your files. By law, real debt collectors must stop calling you if you ask them to in writing.
Do not give the caller personal financial or other sensitive information. Never give out or confirm personal financial or other sensitive information like your bank account, credit card, or Social Security number unless you know whom you're dealing with. Scam artists, like fake debt collectors, can use your information to commit identity theft ? charging your existing credit cards, opening new credit card, checking, or savings accounts, writing fraudulent checks, or taking out loans in your name.
Contact your creditor. If the debt is legitimate ? but you think the collector may not be ? contact your creditor about the calls. Share the information you have about the suspicious calls and find out who, if anyone, the creditor has authorized to collect the debt.
Report the call. Contact the FTC and your state Attorney General's office with information about suspicious callers. Many states have their own debt collection laws in addition to the federal FDCPA. Your Attorney General's office can help you determine your rights under your state's law.

http://www.consumer.ftc.gov/articles/0258-fake-debt-collectors

8552478659 called my parents phone left a ridiculous message saying the call was notifying me that I've been served. That I have to call back asap on civil case.

Do I have to call? I don't want to give any information to dept collection agencies.. I'm not sure how to proceed.

Copied from another thread regarding COASTAL PRE- MITIGATION:

If they are legit, then provide the following:
--FULL COMPANY NAME
--PHYSICAL ADDRESS
--LOCAL TELEPHONE NUMBER
--NAMES OF THE ATTORNEYS
--BAR # OF THE ATTORNEYS
--STATES THE ATTORNEYS ARE LICENSED TO PRACTICE
--STATE OF COMPANY'S REGISTRATION
--LINK TO BBB REPORT

MAYBE, just maybe, we might be inclined to agree with you.  Until then, your advice and comments mean NOTHING.

So you see, "Melissa", it's just another bottom-feeder debt collector trying to come off as a legit company. Schmuck..stop trolling these threads for your employers and making inane comments on their behalf!

person called myself and sister stating they were from harris county law enforcement. Stated if I didn't pay or make arrangements that I would be arrested. This is a collections agent not a police officer. Called back no. and they denied the call.If you are from the state of Texas do not let these people scare you. Only a judge can make a judgement and in Texas you get a judgement but no jail time. If threaten please inform police. In Texas usually they cant put you in jail for owing a bill. Unless Federal or state. They are neither.

Coastal is a prelitigation firm

Good ole' boy with Southern accent called asking for a co-worker who is out. Said she was not in, but could I take a message? He then asked me our company policy for having an employee served on the property. Since we get scare-tactic calls like this all the time from collection agencies here, I said: "Why don't you just give me the name of the collection agency and I will give her the info?" He said that it was a LOCATOR SERVICE, not collections. (PLEASE!) I then told him that we do not allow anyone to be served on company property except by LAW ENFORCEMENT(which is true). Googled the 855 number and nothing came up. Caller ID showed a bunch of zero's.  Called the number back and got "Coastal".