Termite treatments. What is best?

In northern okla our home has termites we have had three different estimates and they are similar in priceing and all use Termidor. All three will drill into the concrete of the house around the front where there is visible signs of termites and then put the chemical in through a trench around the rest of the perimiter of the house. One of the companies will drill about every 24 inches into the morter around the entire perimiter of the house. This is a brick home on a slab foundation. Is it better to have it put into the house all the way around or is the trench methon just as effective? Also one of the outfits that trenches it also puts in monitors and comes back in three months to check for any activity. We don't know what to decide on we want the best possible protection. Thanks for any advice.