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Fix for Siemens Gigaset phones not ringing with Grandstream HT801/HT802 VoIP ATA

This seemed to not be documented anywhere that I was able to find, so I am posting here to hopefully help someone else in the same situation.

When using any model of Siemens Gigaset analogue phones, in my case the C430A but other Gigaset models seem to have the same issue as well, you may find that the phone does not ring for incoming calls however if you pick up the phone while ringing, the call does successfully answer. From my investigation it seems to likely be some regional difference between Gigaset being a German brand, and the UK default settings on the Grandstream ATAs.

To resolve this, there may be some specially wired cable which may do the job, and this is the route I thought I would have to experiment with, however during testing I did manage to find a much simpler solution.

This fix is tested and confirmed working on the HT801 and HT802 models but it will likely work on other models and even other brands if they have the same options. On the web interface for the Grandstream unit, you want to click onto the “FXS Port” page and scroll down to the “SLIC Setting” and set this to “GERMANY”, next, set the “Caller ID Scheme” to “SIN 227 – BT” as shown below and apply the settings.

I do not know whether this will apply to all VoIP providers, but in the case of my testing it was used with www.yay.com who are an excellent provider offering an affordable business VoIP service, well worth a look if you’re in the market for a new provider!

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