Hi, I've got an * box with 4 E1 (TE405P) and a Class 4 Cirpack switch (www.cirpack.com). <IP Network>--<*>--<Cirpack>--<Public PSTN Network> ISDN interco is EuroIsdn, ports are configured ccs, hdb3, crc4. Cirpack is Network, * is Terminal/User. As I encountered some pb with Sip to Zap transcoding (* to Cirpack way poor quality, the other way fine), I tryed to put a loop on * in order to make a 100 % TDM call and qualify only the ISDN side. in zapata.conf, echocancel is on, echocancelwhenbridge is off. A=calling one B=called one both are PSTN terminals 1) Incoming call on my Cirpack from PSTN. 2) Routing to * 3) On *, routing back to Cirpack. 4) On Cirpack, routing to PSTN. => Quality B to A is perfect. Quality A to B is very poor, crackling sound, a strong crackling echo. I am observing the same effect when performing a Sip-to-Zap call. That's a one way problem. If you have any idea, or tweak settings which could help, you're welcome. thieumS * 1.0.5 zaptel 1.0.4