In our case, and I'm sure many others are the same, we cannot ensure uninterrupted connections to the Internet. If our CLEO link fails, for whatever reason, we have no backup.
We did have an ADSL line installed a few years back, but we were informed that this was a 'major security risk' to the LEA's network and if we didn't disconnect it, we would be disconnected from the CLEO network. Which is a perfectly valid point, and I have no problems with it.
Granted, 99% of the time our Internet works, but there is always the chance it won't...