Study design: Single centre randomized three-arm parallel group trial As it is not clear how best to support treatment adherence for people with hypertension we need to compare the different ways this might be done. Eligible patients who provide written consent will be put into one of three groups and then compared. The groups are selected by a computer which has no information about the individual (i.e. by chance). Participants in each group will get different types of SMS-text messages and these are compared.