There are lots of suitable alarms on eBay or alibaba. Here is a good example: http://www.ebay.co.uk/itm/270957633368. You just need a mobile phone SIM card and the alarms are easy to set up by entering the phone numbers to text & call. The sensors are all wireless, the batteries last about a year. The alarm units have built-in backup batteries and they are powered by a low voltage transformer so it's quite straightforward to power them from a simple battery / solar panel if needed. There are special sensors available if needed, i.e. for pets or for use outside. You still need to make friends with your neighbours and ask them to respond for you.