Bizarre Issue between S505 and S500

I have an assortment of both Sangoma S500 and S505 phones.

My problem is as follows: most, but not all of my S500s are experiencing massive packet loss and horrible sound quality. They have packet loss over regular ping, and obviously over any VOIP communication. It’s so bad you can hear the problem during the dial tone. Audio is choppy, words are dropped etc.

My S505s are working flawlessly. I can take an S505 and plug it into the exact same port/wiring/etc in the same location and have crystal clear calls.

This is all across a LAN, no WAN links involved. Internal calls are affected as well as external calls across our POTS service, but the POTS lines sound fine on the S505s.

Does anyone have any idea what’s going on here?

Not without more information about your network. If this is all on the LAN, then there’s something really hinky going on. Are VLANs involved? What switches are you using? How do you configure the phones?

All phones exist on one vlan, they’re routing data traffic back to a different vlan.

The PBX is plugged into an Aruba 2930M stack, which is then run through a 3910M stack to put fiber out to the end user switches. The problem occurs across a variety of end user switches, to keep the questions to a minimum we’ll focus on one UBNT ES-48-750w

This VLAN has voice QOS enabled and is running at QOS 7.

The phones are configured through endpoint manager in FreePBX, so the S500s and S505s have the same config.

The dropped packets occur only on an S500 phone. Again, if I plug an S505 into the exact same wiring, port, etc, the phone works flawlessly.

Further information:

A computer configured to that vlan on the same physical network connection as a malfunctioning S500 performs flawlessly with no packet loss. I can find no packet loss/jitter anywhere else on the network with the exception of communicating to an S500 phone.

Were the 500s ever working without issue? Is it fair to say that the problem is consistent, and noticeable on all calls, all the time? Also, can you tell us the firmware version that is being installed on an s500 having the issues, and a working s505?

They were working without issue up to a couple of weeks ago. It has taken my stubborn self this long to start looking for help.

It is extremely consistent, as in it’s constant.

They’re both using the most recent firmware, x.0.4.75. Older firmware versions do not solve the issue.

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