Agents don't answer their phones

We've only had a couple of agents tell us they didn't like our showing service, AccuShow. The reason is they had to be put on hold. I would rather be put on hold for a minute or two then not be able to show the house.
It's the 3rd of July and most agents are probably working on holiday plans. That's fine, agents need lives too. The problem is that seller's homes are not getting shown because the agents don't answer their phones.

I wish every agent invested in a showing service so I could show my buyer some houses. As a seller, I wouldn't be happy if I knew my agent were not answering his/her phone.