When provisioning new Sangoma S500 handsets the timezone settings for daylight saving are not honoured when timezone is set to GMT. After some testing I found that the daylight saving setting is honoured for any other timeszone (e.g. +1, -1, etc). So this only seems to be a problem with GMT. Settings daylight saving to enabled or disabled makes no difference at all (but as mentioned in any other timezone the daylight saving setting works and moves the time correctly).