constitutional right: ALONE... yep :p

Sec. 3, Article III of the 1987 Philippine Constitution.
(1) The privacy of communication and correspondence shall be inviolable except upon lawful order of the court, or when public safety or order requires otherwise as prescribed by law.
(2) Any evidence obtained in violation of this or the preceding section shall be inadmissible for any purpose in any proceeding.

Is there a constitutional right to privacy?
Yes. The essence of privacy is “the right to be left alone”. It is expressly recognized in Section 3(1) of Article III. Other facts of the right to privacy are protected in various provisions of the Bill of Rights, i.e., Sections 1 (right to due process clause), 2 (right against unreasonable searches and seizures), 6 (right to liberty of abode and of changing the same, as well as the right to travel), 8 (freedom of association) and 17 (right against self-incrimination).
(Ople vs. Torres, G.R. No. 127685, July 23, 1988)

ACCORDING TO...
RA 4200 Anti-Wire Tapping Act
It prohibits any person not being authorized by all parties to any private communication or spoken word, to tap any wire or cable, or by using any other device or arrangement to secretly overhear, intercept or record the same, or to communicate the content thereof to any person.

The use of said record may be permitted in the following instances:
1. In civil or criminal proceedings involving certain specified offenses principally
affecting national security; and
2. When authorized by the court which may be issued under the following conditions:
a. The constitutional requirements for the issuance of a warrant should be
complied with; and
b. The authority shall be effective only for sixty (60) days.
Any evidence obtained in violation of this law is not admissible in any proceeding.
not make any distinction. A telephone extension is not among the devices covered by this law. (Gaanan vs. IAC, 145 SCRA 112)

Navarro vs. CA, G.R. No. 121087, August 26, 1999, two local media men in Lucena City went to the police station to report alleged indecent show in one night establishment in the City. At the station, there was a heated argument between police officer Navarro and Lingan, one of the two media men, which led to fisticuffs. Lingan fell and his head hit the pavement which caused his death. During the trial, Jalbuena, the other

RA 4200 clearly and unequivocally makes it illegal for any person, not authorized
by all parties to any private communication, to secretly record such communications by means of a tape recorder. The law does media man, testified. Presented in evidence to confirm his testimony was a voice recording he had made of the heated discussion at the police station between accused police officer Navarro and the deceased, Lingan, which was taken without the knowledge of the two. The SC held that Jalbuena’s testimony is confirmed by the voice recording he had made. It may be asked whether the tape is admissible in view of RA 4200, which prohibits wire tapping. The answer is in the affirmative. The law prohibits the overhearing, intercepting or recording of private communications. Since the exchange between petitioner Navarro and Lingan was not private, its tape recording is not prohibited.

Exempted acts:
A. Use of such record or any copies thereof as evidence in any civil, criminal
investigation or trial of offenses mentioned below: [Secs. 1, par. 2]
B. Any peace officer, who is authorized by the written order of the Court (RTC
within whose territorial jurisdiction the acts for which authority is applied for are to be executed), to execute any of the acts declared to be unlawful in cases involving the
crimes of: [Sec. 3, par. 1]
1. treason
2. espionage
3. provoking war and disloyalty in case of war
4. piracy
5. mutiny in the high seas
6. rebellion
7. conspiracy and proposal to commit rebellion
8. inciting rebellion
9. sedition
10. conspiracy to commit sedition
11. inciting to sedition
12 kidnapping as defined by the RPC
13.violations of CA 616, punishing espionage and other offenses against
national security

The WRITTEN ORDER shall only be issued or granted upon written application
with the examination under oath or affirmation of the applicant and the witnesses he may produce and must show:
a) That there are reasonable grounds to believe that any of the crimes
enumerated herein has been committed or is being committed provided, that in cases involving the offenses of rebellion, conspiracy and proposal to commit rebellion, inciting to rebellion, sedition, conspiracy to commit sedition, such authority shall be granted only upon prior proof that a rebellion or acts of sedition, as the case may be, have actually been or are being committed;
b) That there are reasonable grounds to believe that evidence may be obtained
essential to the conviction of any person for, or to the solution of, or to the prevention of, any of such crimes;
c) That there are no other means readily available for obtaining such evidence.

NOTE...
Any communication or spoken word, or the existence contents, substance,
purport, effect or meaning of the same or any part thereof, or any information therein contained, obtained or secured by any person in violation of this Act shall not be admissible in evidence in any judicial, quasi-judicial, or administrative hearing or investigation.

Exclusionary Rule
Art. III, Sec. 3. xxx
(2) Any evidence obtained in violation of this (privacy of communication and
correspondence) or the preceding section (unreasonable searches and seizures) shall be inadmissible for any purpose in any proceeding.
One of the remedies of one who was victimized by an illegal search is to ask for the suppression of the things seized and the evidence illegally taken.
The exclusionary rule prohibits the use of any evidence obtained in violation of
Sections 2 and 3 (1), Art. III for "any purpose" and in "any proceeding." The evidence is absolutely useless. This has not always been the case.

But Wait….
Human Security Act of 2007
Section 3, Human Security Act of 2007, provides that the authorities may, upon a written order
of the Court of Appeals, listen to, intercept and record, with the use of any mode, form, kind or type of electronic or other surveillance equipment or intercepting and tracking devices, or with the use of any suitable ways and means for that purpose, any communication, message, conversation, discussion, or spoken or written words between members of terrorist group. Provided, That surveillance, interception and recording of communications between lawyers and clients, doctor and patients, journalists and their sources and confidential business correspondence shall not be
authorized.