When potential survey respondents decide whether or not to participate in a telephone interview, they may consider what it would be like to converse with the interviewer who is currently inviting them to respond, e.g. how he or she sounds, speaks and interacts. In the study that is reported here, we examine the effect of three interactional speech behaviours on the outcome of survey invitations: interviewer fillers (e.g. 'um' and 'uh'), householders' backchannels (e.g. 'uh huh' and 'I see') and simultaneous speech or 'overspeech' between interviewer and householder. We examine how these behaviours are related to householders' decisions to participate (agree), to decline the invitation (refusal) or to defer the decision (scheduled call-back) in a corpus of 1380 audiorecorded survey invitations (contacts). Agreement was highest when interviewers were moderately disfluent—neither robotic nor so disfluent as to appear incompetent. Further, household members produced more backchannels, a behaviour which is often assumed to reflect a listener's engagement, when they ultimately agreed to participate than when they refused. Finally, there was more simultaneous speech in contacts where householders ultimately refused to participate; however, interviewers interrupted household members more when they ultimately scheduled a call-back, seeming to pre-empt householders' attempts to refuse. We discuss implications for hiring and training interviewers, as well as the development of automated speech interviewing systems.