Cable internet quality can be very intermittent depending on many factors.
Your jitter is very high, download QOS is very low at 52% and maximum TCP delay of 679 ms is very high. That's over half a second!
Here are my results:
VoIP test statistics
Jitter: you --> server: 1.1 ms
Jitter: server --> you: 1.2 ms
Packet loss: you --> server: 0.0 %
Packet loss: server --> you: 0.0 %
Packet discards: 0.0 %
Packets out of order: 0.0 %
Estimated MOS score: 4.1
Speed test statistics
Download speed: 1927936 bps
Upload speed: 1092336 bps
Download quality of service: 67 %
Upload quality of service: 92 %
Download test type: socket
Upload test type: socket
Maximum TCP delay: 209 ms
Average download pause: 6 ms
Minimum round trip time to server: 91 ms
Average round trip time to server: 93 ms
Estimated download bandwidth: 2080000bps
Route concurrency: 1.078874
Download TCP forced idle: 0 %
Maximum route speed: 5761312bps
My download QOS is only 67% and does fluctuate a lot but I still get good call quality.
Your download speed is only 400 Kbps and upload of 344 Kbps which is very low for the download. What is the download and upload speed ratings of the service tier you're paying for?
Also, is your Telo connected as option 2A (after modem and before router) or option 2B (after router) from the Telo installation instructions?
I would recommend connecting as 2A and trying that. You may also want to set your QOS in the Telo setup page at http://setup.ooma.com
You may have to work with your ISP to get better results from your internet connection.