This forum includes tips for maintaining the best audio quality possible with the Ooma System. If your Ooma system is having issues with dropped calls, static audio or echo, look here for assistance.
#53336 by dcandmc
Mon Apr 19, 2010 6:01 am
I purchased and installed a Telo unit on Saturday 4/17. I requested a number port from my landline carrier (Fairpoint Communications, formerly Verizon territory), so until that happens I'm still using the landline carrier. In poking around the forum here, I came across this website http://myvoipspeed.visualware.com/. I tested for jitter, and my readings are nearly off the scale bad. I'm consistently getting jitter readings in the 80 to 90 ms range, when the scale annotation tells me that anything over 40 ms won't support VoIP. All my other readings (speed, packet loss, QOS) are generally acceptable. I have cable internet with a Motorola SB4100 modem and a Linksys WRT160N wireless router. The Telo is between the modem and the router.

Questions: am I in for a big disappointment once my number ports and I'm using VoIP for my phone calls? If the jitter numbers that I'm seeing are a problem, is there any way to resolve the problem so that I can use Ooma with decent voice quality? Or should I just cancel the port request and pack up and return the Telo now?
#53339 by murphy
Mon Apr 19, 2010 6:28 am
That modem was declared end of life 10/29/2008. It can't handle Docsis 2.0 or 3.0 . It's a 1.0 modem.
If you are renting the modem from the cable company, take it in and request a new modern modem.
If you own the modem, consider purchasing a Motorola SB6120.
#53347 by dcandmc
Mon Apr 19, 2010 7:48 am
Murphy-
Thanks for the quick reply. Is it reasonable to assume that my older modem is the cause of the high jitter levels? In other words, will the use of a newer modem likely reduce the jitter reading to a level suitable for VoIP?
#53353 by murphy
Mon Apr 19, 2010 8:48 am
dcandmc wrote:Murphy-
Thanks for the quick reply. Is it reasonable to assume that my older modem is the cause of the high jitter levels? In other words, will the use of a newer modem likely reduce the jitter reading to a level suitable for VoIP?

It's hard to say. Comcast is in the process of getting rid of all 1.0 modems because they are not completely compatible with the new 3.0 headend hardware. At some point they will stop working completely.
Try connecting to http://192.168.100.1.
That is the web page inside of the cable modem and should give you the downstream signal level and SNR and the upstream power level. If either of those is out of range it can cause lots of problems. There should only be one split between your incoming cable and the cable modem and the splitter should be a bi-directional splitter good to 1000 MHz.
#53356 by dcandmc
Mon Apr 19, 2010 9:45 am
murphy wrote:It's hard to say. Comcast is in the process of getting rid of all 1.0 modems because they are not completely compatible with the new 3.0 headend hardware. At some point they will stop working completely.
Try connecting to http://192.168.100.1.
That is the web page inside of the cable modem and should give you the downstream signal level and SNR and the upstream power level. If either of those is out of range it can cause lots of problems. There should only be one split between your incoming cable and the cable modem and the splitter should be a bi-directional splitter good to 1000 MHz.


Thanks for the additional information. There is only one split between the incoming cable and the cable modem, with the splitter rated at 1GHz for the broadband output. What specs are considered in range for signal level, SNR and power level?
#53358 by Aveamantium
Mon Apr 19, 2010 10:16 am
dcandmc wrote:
murphy wrote:It's hard to say. Comcast is in the process of getting rid of all 1.0 modems because they are not completely compatible with the new 3.0 headend hardware. At some point they will stop working completely.
Try connecting to http://192.168.100.1.
That is the web page inside of the cable modem and should give you the downstream signal level and SNR and the upstream power level. If either of those is out of range it can cause lots of problems. There should only be one split between your incoming cable and the cable modem and the splitter should be a bi-directional splitter good to 1000 MHz.


Thanks for the additional information. There is only one split between the incoming cable and the cable modem, with the splitter rated at 1GHz for the broadband output. What specs are considered in range for signal level, SNR and power level?

SNR>33
Downstream Power -10 to 10
Upstream Power 40-50
#53360 by dcandmc
Mon Apr 19, 2010 10:33 am
Aveamantium wrote:SNR>33
Downstream Power -10 to 10
Upstream Power 40-50


Downstream SNR is between 34 and 38 dB
Downstream power is -2 dBmV
Upstream power is 49 dBmV
#53376 by murphy
Mon Apr 19, 2010 1:37 pm
dcandmc wrote:
Aveamantium wrote:SNR>33
Downstream Power -10 to 10
Upstream Power 40-50


Downstream SNR is between 34 and 38 dB
Downstream power is -2 dBmV
Upstream power is 49 dBmV

Those are good numbers so that is not the cause of the problem.
#53398 by dcandmc
Mon Apr 19, 2010 5:14 pm
murphy wrote:Those are good numbers so that is not the cause of the problem.


By "that" do you mean my antique modem? Are do you still recommend that I upgrade to a newer modem to reduce the jitter?
#53399 by murphy
Mon Apr 19, 2010 5:40 pm
dcandmc wrote:
murphy wrote:Those are good numbers so that is not the cause of the problem.


By "that" do you mean my antique modem? Are do you still recommend that I upgrade to a newer modem to reduce the jitter?

No, I meant the signal levels are not the cause of the problem. The modem may or may not be the cause of the problem. The only way to know for sure is to swap it out. You didn't say if you are renting the modem. If you are, you can ask for a new one any time that you want one, within reason.

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