Would need to reset device again to confirm but booted Aqua Fish without SIM cards and only used WLAN for first 24 hours; after which switched off and inserted 2 SIMs and set to always ask for which SIM to use to send message and pretty sure it has not tried to send anything. Have checked journalctl entries for last 24 hours.

One week on and without rebooting device elicits this output:-

[root@Sailfish nemo]# systemctl --user status sms-activation-intex.service
sms-activation-intex.service - Sends an activation SMS to Intex
Loaded: loaded (/usr/lib/systemd/user/sms-activation-intex.service; disabled)
Active: inactive (dead) since Thu 2016-08-04 13:48:21 BST; 1 weeks 0 days ago
Process: 15954 ExecStart=/usr/libexec/sms-activation-intex (code=exited, status=0/SUCCESS)
Main PID: 15954 (code=exited, status=0/SUCCESS)
CGroup: /user.slice/user-100000.slice/user@100000.service/sms-activation-intex.service

After rebooting device, elicits this response:

[root@Sailfish nemo]# systemctl --user status sms-activation-intex.timer
sms-activation-intex.timer - Sends an activation SMS after the device has run for 3 hours
Loaded: loaded (/usr/lib/systemd/user/sms-activation-intex.timer; disabled)
Active: active (waiting) since Fri 2016-08-12 06:05:56 BST; 7h ago