How can I reset my alarm??

I bought a house with a veritas alarm back in 2006 but never managed to set it. We had a power cut last week and now the alarm light is flashing outside the house. I don't have a code and understood frmo the previous owner that he had never set it up either. Is there anything I can do to sort this out and reset the alarm with our code without having to pay huge call out charges, etc?