Hi, I've got an * box with 4 E1 (TE405P) and a Class 4 Cirpack switch (www.cirpack.com). <IP Network>--<*>-[TE405P]-<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/zaptel 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 network. 2) Routing to * (TE405P) 3) On *, routing back to Cirpack. (TE405P again) 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 and I notice it happens only when * initiates a zaptel channel (for exemple, zap to sip calls are good in both ways) My card is alone on its IRQ, is taking synchro from my Cirpack on the first port. If you have any idea, or tweak settings which could help, you're welcome. thieumS * 1.0.6 zaptel 1.0.6 libpri 1.0.6 (I tryed with CVS also, same problem)