Hi,
I have similar problem running on Centos 7.5 ans using pulseaudio, my CPU goes to 97% and not RTP packages goes out.
If I try disabling the audio with --null-audio and the CPU is ok.
pjsua-x86_64-unknown-linux-gnu sip:100@ip_address --quality=N --null-audio

I did more test running pjsystest and no audio, see below the results.I tested the audio card with aplay and it plays the wav file.# aplay ../../tests/pjsua/wavs/input.8.wavaplay

./pjsip-apps/bin/pjsystest-x86_64-unknown-linux-gnu

13:07:50.761 os_core_unix.c !pjlib 2.6 for POSIX initialized
13:07:50.762 sip_endpoint.c  .Creating endpoint instance...
13:07:50.762          pjlib  .select() I/O Queue created (0x19d3ff0)
13:07:50.762 sip_endpoint.c  .Module "mod-msg-print" registered
13:07:50.762 sip_transport.  .Transport manager created.
13:07:50.762   pjsua_core.c  .PJSUA state changed: NULL --> CREATED
13:07:50.762 sip_endpoint.c  .Module "mod-pjsua-log" registered
13:07:50.762 sip_endpoint.c  .Module "mod-tsx-layer" registered
13:07:50.762 sip_endpoint.c  .Module "mod-stateful-util" registered
13:07:50.762 sip_endpoint.c  .Module "mod-ua" registered
13:07:50.762 sip_endpoint.c  .Module "mod-100rel" registered
13:07:50.762 sip_endpoint.c  .Module "mod-pjsua" registered
13:07:50.762 sip_endpoint.c  .Module "mod-invite" registered
13:07:50.889     alsa_dev.c  ..ALSA driver found 8 devices
13:07:50.889     alsa_dev.c  ..ALSA initialized
13:07:50.890          pjlib  ..select() I/O Queue created (0x1a02788)
13:07:50.894 sip_endpoint.c  .Module "mod-evsub" registered
13:07:50.894 sip_endpoint.c  .Module "mod-presence" registered
13:07:50.895 sip_endpoint.c  .Module "mod-mwi" registered
13:07:50.895 sip_endpoint.c  .Module "mod-refer" registered
13:07:50.895 sip_endpoint.c  .Module "mod-pjsua-pres" registered
13:07:50.895 sip_endpoint.c  .Module "mod-pjsua-im" registered
13:07:50.895 sip_endpoint.c  .Module "mod-pjsua-options" registered
13:07:50.895   pjsua_core.c  .1 SIP worker threads created
13:07:50.895   pjsua_core.c  .pjsua version 2.6 for Linux-3.10.3.94/x86_64/glibc-2.17 initialized
13:07:50.895   pjsua_core.c  .PJSUA state changed: CREATED --> INIT
13:07:50.895   pjsua_core.c  PJSUA state changed: INIT --> STARTING
13:07:50.895 sip_endpoint.c  .Module "mod-unsolicited-mwi" registered
13:07:50.895   pjsua_core.c  .PJSUA state changed: STARTING --> RUNNING
M E N U :

0: Tests
  00: Run test wizard
  01: Device Test
  02: Play Tone
  03: Play WAV File1
  04: Play WAV File2
  05: Record Audio
  06: Latency Test
  07: AEC/AES Test  09: Exit
1: Options
  10: View Devices
  11: View SettingsEnter the menu number: 00
13:07:55.434      systest.c  Running test wizard
13:07:55.434      systest.c  Running Audio Device List
Audio Device List
Found 8 devices
  0: ALSA [pulse] (1/1)
  1: ALSA [sysdefault:CARD=I82801AAICH] (1/1)
  2: ALSA [front:CARD=I82801AAICH,DEV=0] (1/1)
  3: ALSA [surround21:CARD=I82801AAICH,DEV=0] (1/1)
  4: ALSA [surround40:CARD=I82801AAICH,DEV=0] (1/1)
  5: ALSA [surround41:CARD=I82801AAICH,DEV=0] (1/1)
  6: ALSA [surround50:CARD=I82801AAICH,DEV=0] (1/1)
  7: ALSA [surround51:CARD=I82801AAICH,DEV=0] (1/1)1:OK 
1
13:08:05.707      systest.c  Running Audio Settings
Audio Settings
Version: 2.6
Test clock rate: 8000
Device clock rate: 8000
Aud frame ptime: 20
Channel count: 1
Audio switching: Conf bridge
Snd buff count: 8
Rec dev : -1 (pulse) [ALSA]
Rec  buf : 100 msec
Play dev: -2 (pulse) [ALSA]
Play buf: 140 msec1:OK 
1
Audio Tone Playback Test
This test will play simple ringback tone to the speaker. Please listen carefully for audio impairments such as stutter. You may need to let this test running for a while to make sure that everything is okay. Press OK to start, CANCEL to skip
1:OK  9:Cancel 
1
13:08:16.641      systest.c  Running Audio Tone Playback Test
13:08:16.641    pjsua_aud.c  Conf connect: 1 --> 0
13:08:16.641    pjsua_aud.c  .Set sound device: capture=-1, playback=-2
13:08:16.641    pjsua_aud.c  ..Opening sound device (speaker + mic) PCM@8000/1/20ms
13:08:16.695   conference.c  .Port 1 (ringback) transmitting to port 0 (pulse)
Audio Tone Playback Test
Ringback tone should be playing now in the speaker. Press OK to stop.
1:OK 
1
Audio Tone Playback Test
Is the audio okay?
1:Yes  0:No 
13:08:32.574    pjsua_aud.c !Closing sound device after idle for 0 second(s)
13:08:32.574    pjsua_aud.c  .Closing pulse sound playback device and pulse sound capture device
13:09:18.585     alsa_dev.c !ALSA lib: PulseAudio: Unable to create stream: Timeout

Hi,
I added this error in stackoverflow, if I use any previous versions like 2.7 it works fine.
https://stackoverflow.com/questions/53507832/pjsip-2-8-transport-adapter-sample-segmentation-fault?noredirect=1#comment94003334_53507832

Thanks