This randomized controlled trial tested whether extended callback counselling that proactively engaged ex-smokers with the task of embracing a smoke-free lifestyle (four to six calls delivered 1–3 months after quitting, i.e. when craving levels and perceived need for help had declined) could reduce relapse compared with a revised version of Quitline’s standard service (four calls in the first month after quitting which focused primarily on the task of helping ex-smokers deal with daily cravings and now also systematically alerted clients to the upcoming task of adapting to life as a non-smoker). One thousand and four hundred and forty-four smokers or recent ex-smokers were randomized at recruitment: 734 usual care and 710 intervention. An inclusion criterion of subsequently quitting for at least 1 week gave 346 usual care and 352 intervention participants. Seventy-four per cent of intervention participants accepted extra calls and received 4.3 on average but only 1.7 more post-quitting calls than usual care group. No significant differences were found between extended contact and usual care groups on continuous abstinence (both 27% at 12 months) or any other cessation outcome. The tasks of quitting framework introduced in preparation for the trial might have contributed to service improvement in relapse prevention (10% increased quit rate compared with an earlier trial). However, the extra sessions did not provide any benefit.