Пока плохо. Обычное тестирование на слух показывает дрожание на входящем направлении, вне зависимости от наличия эхоподавления.

Возможно, данные подаются неравномерно. Возможно, они где-то теряются.
Первый звонок гарантированно срывается примерно так:
Dec 29 18:11:58 NOTICE[3014]: chan_zap.c:8221 pri_dchannel: PRI got event: HDLC Abort (6) on Primary D-channel of span 1
Dec 29 18:11:59 NOTICE[3014]: chan_zap.c:8221 pri_dchannel: PRI got event: HDLC Abort (6) on Primary D-channel of span 1
Dec 29 18:12:00 NOTICE[3014]: chan_zap.c:8221 pri_dchannel: PRI got event: HDLC Bad FCS (8) on Primary D-channel of span 1
== Primary D-Channel on span 1 down
Dec 29 18:12:01 WARNING[3014]: chan_zap.c:2303 pri_find_dchan: No D-channels available! Using Primary channel 16 as D-channel anyway!
-- Hungup 'IAX2/gw9-16384'
== Spawn extension (macro-std-iax, s, 1) exited non-zero on 'Zap/1-1' in macro 'std-iax'
== Spawn extension (macro-std-iax, s, 1) exited non-zero on 'Zap/1-1'
Dec 29 18:12:01 NOTICE[3014]: chan_zap.c:8221 pri_dchannel: PRI got event: HDLC Bad FCS (8) on Primary D-channel of span 1
!! Got S-frame while link down
-- Hungup 'Zap/1-1'
Dec 29 18:12:01 NOTICE[3014]: chan_zap.c:8221 pri_dchannel: PRI got event: HDLC Bad FCS (8) on Primary D-channel of span 1
!! Got S-frame while link down
!! Got I-frame while link state 2
Dec 29 18:12:03 NOTICE[3014]: chan_zap.c:8221 pri_dchannel: PRI got event: HDLC Bad FCS (8) on Primary D-channel of span 1
!! Got S-frame while link down
!! Got I-frame while link state 2
== Primary D-Channel on span 1 down
Dec 29 18:12:04 WARNING[3014]: chan_zap.c:2303 pri_find_dchan: No D-channels available! Using Primary channel 16 as D-channel anyway!
== Primary D-Channel on span 1 up