Problem with phone (voip) over new modem setup

I just noticed that the phone quality with my new setup as mentioned in the last posts is bad. The ringing sound is almost echoing and when someone on the other end speaks it is like I am on a bad modem dial-up connection. Arghhhh!!! Do I need to blame my new D-Link modem or did I forget an important setting in both of my DSL-modems? I am receiving a call from my best friend from Germany tonight and am ready to pull the new modem apart and go back to my old setup. I cannot even ask anyone for ideas, because my setup is pretty rare, I guess…maybe I do need to put my German modem first and the Australian modem second? But then I wonder how to receive the high speed internet, if my German modem is not receiving it, plus I also want to use the wireless of the German modem… Would be easier to draw a picture to explain what I mean. Okay, here is my setup:

Looks easy, but took me a while to setup the software of both modems to actually work with each other. However, the phone seems to not get the decent amount of bytes through the line as the sound is just shabby. Also, as I said yesterday, our internet speed is still very much the same as before the new modem came into play. I guess, that the D-Link modem is not transfering the whole speed to the Fritzbox modem. But, where to check and what to set where and why??? HELP!

UPDATE
Just found out that I can call out, but the person on the other end can’t hear me.

Connecting new Aussie ADSL2 modem with wireless German DSL modem

Finally I have time to install the new DSL (ADSL2+) modem that I’ve ordered on eBay a few weeks ago. It is brand new, cost me only $30 (plus shipping extra $15), and is supposed to be a good DSL modem, as far I could search in diverse forums for user opinions. For geeks, it is the D-Link DSL-502T, Generation II, ADSL2+ modem router.

My plan is to connect it to my German wireless DSL modem. With only my German modem, which I changed from Annex B to Annex A (Australian Standard), the DSL speed seems to be, ehm, very slow. We reach not more than 900 kb/sec as download speed, around 500 kb/sec upload. Our internet provider gives us up to 24000 kb/s download speed and we can’t use it so far, but we pay our $60 per month. Therefore, I listened to Sven from the other side of this country (Sydney), who said, he had the same slow internet connections with his German DSL modem, therefore he bought a simple Australian DSL modem to put it as transmitter in between phone line and German DSL modem.
If you don’t see me for a while it can mean that I’m having trouble with getting the internet running. Wish me luck!