When speaking to the company ask "do you need to come into the house". If they say "no" I would ask them to have a nice day and continue to call another company. They are not doing a complete blowout or are expecting you to do one of the most important procedures of the winterization.
It is a common practice that some individuals or companies operate your valves from the outside irrigation box. They open the valves manually, if the valves are less than 5 years old this may not cause damage to your system. Older valves may open fine, but sometimes the valve may not close. In the spring, when time to startup the system, this is the cause of a stuck "open" zone. This leads to an unnecessary repair appointment, some individuals or companies may look at this as "job security".
* Older properties may have an in ground shutoff. This is known as a "stop waste valve" and requires a "T handle" about 4 to 6 feet long to shut off the water to the sprinkler system.