Police officers are not required to administer Miranda warnings to everyone they question, only those they subject to custodial interrogation. (Oregon v. Mathiason (1977) 429 U.S. 492, 495; People v. Ochoa (1998) 19 Cal.4th 353, 401 (Ochoa).) "'Absent "custodial interrogation," Miranda simply does not come into play.'" (Ochoa, supra, at p. 401.) For purposes of Miranda, a person is in custody when there is "'a "formal arrest or restraint on freedom of movement" of the degree associated with a formal arrest.'" (Thompson v. Keohane (1995) 516 U.S. 99, 112; Ochoa, supra, at p. 401.) But he is not in custody if, under the circumstances, "'a reasonable person in his position would have felt free to end the questioning and leave.'" (People v. Leonard (2007) 40 Cal.4th 1370, 1400.) "Custody determinations are resolved by an objective standard: Would a reasonable person interpret the restraints used by the police as tantamount to a formal arrest? . The totality of the circumstances surrounding an incident must be considered as a whole." (People v. Pilster (2006) 138 Cal.App.4th 1395, 1403 (Pilster).) The scope of our review of a claim that a statement or confession is inadmissible because it was obtained in violation of a defendant's Fifth Amendment rights is well established. The Fifth Amendment to the United States Constitution provides no person "shall be compelled in any criminal case to be a witness against himself." (U.S. Const., 5th Amend.) In Miranda v. Arizona, the United States Supreme Court held the privilege is "fully applicable during a period of custodial interrogation." (Miranda v. Arizona (1966) 384 U.S. 436 at pp. 460-461.) Thus, the prosecution may not use a defendant's statements obtained during custodial interrogation by law enforcement unless, prior to questioning, the defendant is advised of his or her rights to silence, to consult with a lawyer, to have the lawyer with him during interrogation and to appointed counsel. (Id. at p. 471.) In Miranda, the United States Supreme Court explained that these warnings were needed to safeguard the individual's Fifth Amendment privilege against the "inherently compelling pressures" of in-custody interrogation "which work to undermine the individual's will to resist and to compel him to speak where he would not otherwise do so freely." (Miranda, supra, 384 U.S. at p. 467.) If an individual subject to custodial interrogation requests a lawyer, the interrogation must stop until the individual's counsel is present, unless the individual initiates further communication, exchanges, or conversations with the police. (Minnick v. Mississippi (1990) 498 U.S. 146, 153 (Minnick); Edwards v. Arizona (1981) 451 U.S. 477, 484-485 (Edwards).) The right to counsel under Miranda does not attach and cannot be invoked outside of the context of custodial interrogation. (Montejo v. Louisiana (2009) 556 U.S. 129 "If the defendant is not in custody, then the Miranda/Edwards decisions do not apply"; see also id. at p. 2091, quoting McNeil v. Wisconsin (1991) 501 U.S. 171, 182, fn. 3 " 'We have in fact never held that a person can invoke his Miranda rights anticipatorily, in a context other than "custodial interrogation" ' "; People v. Nguyen (2005) 132 Cal.App.4th 350, 355 defendant who called attorney during arrest but before interrogation did not effectively assert right to counsel; People v. Avila (1999) 75 Cal.App.4th 416, 422 & fn. 8 because Miranda rights cannot be invoked except during custodial interrogation, accused being arraigned on one charge cannot prospectively invoke his or her Miranda rights to counsel as to some other unrelated charge by a written "invocation of rights" form.) " 'We must accept the trial court's resolution of disputed facts and inferences, and its evaluations of credibility, if they are substantially supported. However, we must independently determine from the undisputed facts, and those properly found by the trial court, whether the challenged statement was illegally obtained.' We apply federal standards in reviewing defendant's claim that the challenged statements were elicited from him in violation of Miranda." (People v. Bradford (1997) 14 Cal.4th 1005, 1033; People v. Buskirk (2009) 175 Cal.App.4th 1436, 1447-1448; People v. Memro (1995) 11 Cal.4th 786, 827 trial court's assessment of credibility of police officers and defendant's witnesses at suppression hearing must be accepted on appeal, if supported by substantial evidence.) For a defendant's statements to be admissible against him, he must have knowingly and intelligently waived his rights to remain silent, and to the assistance and presence of counsel. (Miranda v. Arizona (1966) 384 U.S. 436 at p. 475.) However, a suspect who wishes to waive his Miranda rights and submit to interrogation by law enforcement officers need not do so with any particular words or phrases. (People v. Cruz (2008) 44 Cal.4th 636, 667.) "A valid waiver need not be of predetermined form, but instead must reflect that the suspect in fact knowingly and voluntarily waived the rights delineated in the Miranda decision." (Ibid.) Indeed, a valid waiver of Miranda rights may be either express or implied. (People v. Whitson (1998) 17 Cal.4th 229, 246-247 discussing relevant federal and state high court authorities.) Moreover, an accused's "expressed willingness to answer questions after acknowledging an understanding of his or her Miranda rights has itself been held sufficient to constitute an implied waiver of such rights. In contrast, an unambiguous request for counsel or refusal to talk bars further questioning." (People v. Cruz, supra, 44 Cal.4th at pp. 667-668.) Finally, while there is a threshold presumption against finding a Miranda rights waiver, ultimately the question is whether, under the totality of circumstances surrounding the interrogation, the waiver was knowing and intelligent. (Id. at p. 668.) The law is well established that "when reviewing a trial court's decision on a motion that statements were collected in violation of the defendant's rights under Miranda v. Arizona (1966) 384 U.S. 436, we defer to the trial court's resolution of disputed facts, including the credibility of witnesses, if that resolution is supported by substantial evidence. Considering those facts, as found, together with the undisputed facts, we independently determine whether the challenged statements were obtained in violation of Miranda's rules, that is, whether (assuming the defendant was in custody) the statements were preceded by the now-famous admonition of Miranda rights: the defendant has the right to remain silent, any statement he might make can be used against him, he has the right to the presence of an attorney, and an attorney will be provided at state expense if he cannot afford one. " (People v. Weaver (2001) 26 Cal.4th 876.) Once a custodial defendant has "expressed his desire to deal with the police only through counsel, he is not subject to further interrogation by the authorities until counsel has been made available to him, unless the accused himself initiates further communication, exchanges, or conversations with the police." (Edwards v. Arizona, supra, 451 U.S. 477 at pp. 484-485.) "If police officers subsequently question the suspect in counsel's absence, assuming there has been no break in custody, the suspect's statements are presumed involuntary even where the suspect waives his Miranda rights and voluntarily agrees to speak with investigating officers. This bright-line rule is 'designed to prevent police from badgering a defendant into waiving his previously asserted Miranda rights.' The Edwards rule, moreover, is not offense-specific: Once a suspect invokes the Miranda right to counsel for interrogation regarding one offense, officers may not seek the suspect's permission to discuss other crimes unless counsel is present. " (People v. Nguyen, supra, 132 Cal.App.4th at p. 354 (Nguyen).) However, the Edwards rule applies "only when the suspect 'has clearly expressed' his wish for the particular sort of lawyerly assistance that is the subject of Miranda. It requires, at a minimum, some statement that can reasonably be construed to be an expression of a desire for the assistance of an attorney in dealing with custodial interrogation by the police." (McNeil v. Wisconsin, supra, 501 U.S. at p. 178.) As the high court in McNeil observed, it had "never held that a person can invoke his Miranda rights anticipatorily, in a context other than 'custodial interrogation' ... ." (Id. at p. 182, fn. 3.) Thus, "in order for a defendant to invoke his Miranda rights the authorities must be conducting interrogation, or interrogation must be imminent." (U.S. v. LaGrone (7th Cir. 1994) 43 F.3d 332, 339; see also Nguyen, supra, 132 Cal.App.4th at p. 357; People v. Beltran (1999) 75 Cal.App.4th 425, 432; People v. Calderon (1997) 54 Cal.App.4th 766, 770-771.) Although a defendant is not required to wait until a formal Miranda admonition before invoking the right to counsel, the circumstances must be such that the custodial defendant could reasonably conclude that interrogation is pending or imminent (Nguyen, supra, 132 Cal.App.4th at p. 357) and that a reasonable officer would know that the defendant's request for counsel was unequivocal for purposes of the interrogation (People v. Gonzalez (2005) 34 Cal.4th 1111, 1123-1125 23 Cal. Rptr. 3d 295, 104 P.3d 98). Because "it is the premise of Miranda that the danger of coercion results from the interaction of custody and official interrogation" (Illinois v. Perkins (1990) 496 U.S. 292, 297), "the special procedural safeguards outlined in Miranda are required not where a suspect is simply taken into custody, but rather where a suspect in custody is subjected to interrogation." (Rhode Island v. Innis (1980) 446 U.S. 291, 300) Interrogation consists of express questioning or words or actions on the part of the police that "are reasonably likely to elicit an incriminating response from the suspect." (Id. at p. 301.) In other words, "'the police may speak to a suspect in custody as long as the speech would not reasonably be construed as calling for an incriminating response.'" (People v. Cunningham (2001) 25 Cal.4th 926, 993.) "In deciding whether police conduct was 'reasonably likely' to elicit an incriminating response from the suspect, we consider primarily the perceptions of the suspect rather than the intent of the police. " (People v. Davis (2005) 36 Cal.4th 510, 554.) Miranda applies only to custodial interrogations. (People v. Ochoa (1998) 19 Cal.4th 353, 401.) In reviewing the trial court's determination that defendant was not in custody, we apply a deferential substantial evidence standard of review to the trial court's conclusions regarding the historical facts. (Id. at p. 402.) We independently review the mixed question of law and fact regarding whether a reasonable person would have felt free to terminate the interrogation. (Ibid.) The prosecution bears the burden of demonstrating the validity of a defendant's waiver of his Miranda rights by a preponderance of the evidence. (People v. Dykes (2009) 46 Cal.4th 731, 751.) Additionally, "'although there is a threshold presumption against finding a waiver of Miranda rights , ultimately the question becomes whether the Miranda waiver was voluntary, knowing, and intelligent under the totality of the circumstances surrounding the interrogation.' " (People v. Williams (2010) 49 Cal.4th 405, 425 (Williams).) After Miranda warnings are given, the interrogation must cease if the suspect indicates he wishes to remain silent or states he wants an attorney. The state bears the burden by a preponderance of the evidence to show that a suspect's waiver was knowing, intelligent, and voluntary under the totality of the circumstances surrounding the interrogation. (People v. Williams (2010) 49 Cal.4th 405, 425; People v. Cruz (2008) 44 Ca1.4th 636, 668.) After a knowing and voluntary waiver, an interrogation may continue unless the suspect clearly requests an attorney. (Williams, at p. 427.) In the absence of an unambiguous or unequivocal invocation, the interrogating officer has no obligation to end the interrogation or ask the suspect any clarifying questions. (Berghuis v. Thompkins (2010) 560 U.S. 370, 381; People v. Martinez (2010) 47 Cal.4th 911, 948.) However, the interrogator may try to clarify the suspect's intention. (People v. Williams, supra, 49 Cal.4th at p. 428.) Ambiguity is determined objectively; statements deemed ambiguous are those that "a reasonable officer in light of the circumstances would have understood to signify only that the suspect might be invoking" his Miranda rights. (Davis v. United States (1994) 512 U.S. 452, 459; see Williams, at p. 428.) In considering a Miranda violation on appeal, this court independently reviews the trial court's legal determination and defers to its factual findings if substantial evidence supports them. (Williams, at p. 425.)