Most of all trust your instincts, if you called and they have answered all your questions and some questions that you didn't ask. There are probably a reputable service provider. If they are evasive, using high pressure sales, seem to be more interested in signing you up instead of giving you all information you need to evaluate other companies, they don't have your best interests in mind.
The Equipment
Here here is where is extremely easy. There is truly only one in alarm equipment company, the inventor of the panic button. Linear has led the market in alarm control and monitoring systems. Linear LLC offers a full spectrum of advanced alarm monitoring components, on a worldwide basis, for the residential and commercial security market. It has been designing and building for this market for over 48 years and is regarded as one of the founders and leaders of the contemporary security industry.
Last but definitely the most important the Call Center
First off make sure that your service provider is using a UL listed Central call station with a separate Pers division. If they are using a regular security alarm operators run away as fast as you can. It is imperative that they use a call station that has a separate division of Pers trained operators.
Why Pers trained operators?
All PERS operators go through extensive training on the proper response to medical alarm systems. Their pledge is to treat each customer as though they were their own parent or grandparent and provide the most dignified, appropriate, and expedient response to every alarm. Make sure that the Pers trained operator will stay on line until the problem has been resolved. PERS operators encourage the elderly to use the alarm no matter how small the problem is, the cat got out, my kids haven't called me for a week, I'm lonely. They realize the more that they can get them to push the button and talk to them, when they need to push the button they will. The call center should only monitor for professional medical alarm companies, not directly to the general public. Most monitoring stations also sell, service, and install equipment.
Monitoring should be left to the professionals