Hello, 1-2 sec pauses happen while * plays (streams) messages/prompts. We get reports about that from users and experience it ourselves randomly. Cannot reproduce it for debugging though, so need to figure out some other ways to fix it. 1. It's not silence recorded within or pauses between audio files 2. It's not load related - can happen with no load at all 3. We use decent boxes - dual 3.2GHz, 2 Gb RAM, RH9 2.4.22 #4 SMP 2 TE410P (with SMP affinity), PRI 4. It happens on PRI calls 5. Asterisk compiled with ZAPTEL_OPTIMIZATIONS 6. zttest output: --- Results after 84 passes --- Best: 100.000000 -- Worst: 99.987793 Questions: 1. Can we ask to explain how buffer underrun is implemented? We could not figure it out by looking at file.c and zaptel with ZAPTEL_OPTIMIZATIONS. 2. Which asterisk parameters/configuration vars could help? Any suggestions on Linux configuration (IO related or any other)? Thank you. Alex Zarubin Webley Systems