Grandstream HT813 ATA

Hi everyone,

Does anyone have any experience in using a Grandstream HT813 as their ATA FXO PSTN (POTS) interconnect with FreePBX.

I am currently using a Cisco SPA3102 with poor audio results (echo and clipping).



Though I have no experience with HT813 (or any Grandstream FXO device), my system has both an SPA3102 and an Obihai OBi110 (in different locations) and I’m familiar with the problems.

Assuming that this is for your system in Guildford:

The SPA3102 is notorious for echo problems. Its echo canceler can handle a tail of only a few milliseconds, which is insufficient to handle regional calls with a longer echo path that is still too short to require carrier echo cancellation. For example, you might experience echo on a call to or from Liverpool, but London calls would be fine (echo within range of the SPA’s canceler), as would Edinburgh (BT canceler in the path). Obihai products do not have this deficiency. (This issue relates to echo that the PBX user hears. Any echo heard by the remote party is being introduced elsewhere and requires separate troubleshooting.)

Have you tried controlling echo by reducing the gains on the FXO port? For example, try SPA To PSTN Gain: -6 and PSTN To SPA Gain: 0. If the volume level in both directions is still acceptable, this may be an adequate fix. You might also try More Echo Suppression: yes, though that will degrade doubletalk performance. Possibly, changing the port impedance will help (even though BT claims to be 600 ohms).

By ‘clipping’, do you mean severe distortion caused by exceeding the dynamic range of the A/D converter or the analog hardware? If so, reducing the gains should fix that. Or, do you mean that one party’s voice is blocked while the other is speaking? Unfortunately, that’s nearly impossible to fix when analog lines are involved.

Do you have a SIP trunk on your system? Though not free, SIP calls to UK are very inexpensive and you’ll enjoy better voice quality, no channel limitations (you can make or receive calls while e.g. your wife is on the phone), faster call setup, better logging (CDRs will correctly show whether a call was answered), etc. UK rates on Voxbeam, using their ‘Platinum’ route (my account is in US dollars): landlines: $0.0022/min.; major mobiles: $0.0072 to $0.0083. When you sign up, they provide a small credit, so you can test without making a payment.

Huh the HT-813 is new. We are constantly replacing other brands with grandstream HT-XXX models and they work great for ATA’s. The HT-(812|814) both work nicely.

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