All general questions and discussion related to energy
I think the PER can only operate by use of SMS as the system needs to operate quickly with a lot of automation.
To make this work for you while away you will either need to work out a way to send/receive texts from your home phone account, or have someone else act as a proxy for you at home.
Would it be possible for an acquaintance to monitor and respond in your absence. This would mean leaving your SIM here. It could also impact on your privacy. I guess another option would be to assign the phone number for the PER to someone else during your absence and then change it back on your return.