NEW BP-B210N-21/2600S RCA TECHNICOLOR TC8305C EMTA CABLE MODEM BACKUP BATTERY

I bought this battery since I had a modem years ago that had an internal battery backup and I wanted the same functionality.I have my modem connected to a UPS, but it frankly doesn't last long enough. On the previous modem, the internal battery actually gave me hours of backup power. I had hoped for the same here.Here's a rundown on the problems:1) The battery only backs up the phone connection. Unlike the previous generation modem, the internal battery does not keep the modem online. This is exactly the opposite of useful since it's far easier to back up my phone service with my cell than it is to back up my internet with it.2) It doesn't actually back up the phone connection reliably. After I had a reset power disconnect, the phone was unusable even after power was restored. The entire time, all I got was the busy signal on my digital voice line that indicated the service was not available.3) Neither the voice service or internet service would come back until I pulled the battery, even after resetting the modem multiple times. In other words, the battery was preventing the modem from properly resetting, so it couldn't re-establish a connection.Summary: the battery makes everything worse. I'm better off just getting a larger UPS.Don't bother with this.

Unlike the product info, this is not compatible with the the Comcast TC8305C cable modem.While it has the correct physical electrical connection, it does not fit into the back up battery slot.