There is a reciprocal relationship between trust and vocal communication in human interactions. On one hand, a predisposition towards trust is necessary for communication to be meaningful and effective. On the other hand, we use vocal cues to signal our own trustworthiness and to infer it from the speech of others. Research on trustworthiness attributions to vocal characteristics is scarce and contradictory, however, being typically based on explicit judgements which may not predict actual trust-oriented behaviour. We use a game theory paradigm to examine the influence of speaker accent and prosody on trusting behaviour towards a simulated game partner, who responds either trustworthily or untrustworthily in an investment game. We found that speaking in a non-regional standard accent increases trust, as does relatively slow articulation rate. The effect of accent persists over time, despite the accumulation of clear evidence regarding the speaker’s level of trustworthiness in a negotiated interaction. Accents perceived as positive for trust can maintain this benefit even in the face of behavioural evidence of untrustworthiness.