Introduction Online NHS111 was introduced in 2018 in response to increasing and unsustainable demand for Telephone NHS111. We explored user and staff perspectives of telephone and online NHS111 to understand how the two services were used, and whether and how online NHS111 had potential to reduce demand for telephone NHS111. Methods We used a convergent parallel mixed methods design, using data from the national online NHS 111 user survey and telephone user survey for 2 NHS 111 areas and semi-structured interviews with 32 recent users of online 111 and 16 NHS 111 staff. We analysed survey data for 3728 online users and 795 telephone users in SPSS, using chi-squared test for proportions and adjusting for age, sex, ethnicity and presence of long-term conditions. Qualitative data was analysed using Framework Analysis. Results Telephone NHS111 health adviser skills in probing and obtaining "soft information" were key to obtaining advice that was considered more appropriate and trusted than advice from online interactions, which relied on over-simplified or inappropriate questions. Telephone users were more satisfied with NHS111 than online users for all comparable measures, reported higher compliance with advice and were more likely to say they would have contacted another service if they had not used NHS111 (p<0.001) . Online NHS111 was perceived to provide a useful and convenient adjunct to the telephone service and widened access to NHS111 services for some subgroups of users who would not otherwise access the telephone service (e.g. communication barriers, social anxiety), or were concerned about "bothering" a health professional. The nature of the online consultation meant that online NHS111 was perceived as more disposable and used more speculatively. Conclusion Online 111 was perceived as a useful adjunct but not replacement for telephone NHS 111 with potential for channel shift hindered by reduced confidence in the online service.

The authors have declared no competing interest.

The study was funded by National Institute for Health Research (NIHR HSDR 127655)

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Ethics approval for the interview-based work with service users and stakeholders was granted by North West Haydock Research Ethics Committee (reference 19.NW/0361). The University of Sheffield Research Ethics Committee granted ethics approval for the telephone and online NHS 111 user surveys (reference 030991)

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