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SPA-400 call dropping

Dear all,

I've set up a SPA-9000 + SPA-400 system in Italy.

SPA-400 configuration:


6 voice mail users, barely used

Three PSTN lines connected (two from FASTWEB carrier, one from TELECOM carrier)

I'm having many problems with calls dropping, apparently with FASTWEB lines. FASTWEB lines come out from a router AETHRA model SV6044 ( As I understand (being a newbie in telecom), they are voip lines which the AETHRA converts to FXS analogic lines. The dropping time of calls is very variable, going from less than one minute to ten or fifteen minutes. Instead, when connecting an analogic telephone to the AETHRA FXS port, we never had a call dropped.

I would exclude high load of SPA-400: although it has 3 lines connected,  the traffic is very poor. The call drops even when is the only one used  in the moment of drop.

With TELECOM carrier seems that SPA-400 works better; never had a call dropped until now.

Is there a possibility of some lack of compatibility with the two components? All the PSTN settings from the SPA-400 are less or none documented, so it is pretty impossible to being sure that they are correctly set for the AETHRA SV6044. They states to be compliant to Q.552 requirements. Does it mean that default PSTN settings from SPA-400 will work?

I would also exclude problems with PBX configuration (SPA-9000), as voip lines configured with it don't have dropping problems.

I could post and attach a syslog report from SPA-400 and SPA-9000, but being very verbose, I will do it if there is a good chance of understanding the problem from it (meaning that for me it's very unclear to understand the cause of the problem just by looking at the syslog).

I'm mostly frustrated because if I don't find a solutions, I am still not clear of what are the alternatives. Finding another gateway Voip-PSTN that works better of SPA-400? SPA-8000? Grandstream GXW-4104? Asking FASTWEB to have the lines in ISDN BRI instead of FXS? And then? Which gateway from Voip to ISDN?

I will surely appreciate any help to my doubt.

Best regards

Maurizio Oliveri


Frequent Contributor

The lines of the spa400 need to connect to the pstn fxo only.  Do not connect to router which is trying emulate those lines.