I’ve hit this exact roadblock when tuning Asterisk’s PJSIP module for higher call concurrency—let’s break down why your config changes might not be sticking, and walk through actionable fixes.

1. Confirm config_site.h is in the Right Place and Loaded During Compilation #

PJSIP won’t pick up your custom config_site.h unless it’s placed in pjlib/include/pj/ (relative to your PJSIP source root). If you stored it elsewhere, you need to explicitly tell the compiler where to find it when configuring PJSIP:

./configure CFLAGS="-I/path/to/your/config/directory"

To verify your macros were applied, check the compilation output for lines like:

-DPJSUA_MAX_CALLS=128

Or inspect the generated pjlib/include/pj/config.h—your custom values should override the default 32-call limit.

2. Don’t Stop at PJSUA_MAX_CALLS—Tune Complementary PJSIP Macros #

Increasing just PJSUA_MAX_CALLS isn’t enough; you need to adjust related settings to avoid resource bottlenecks. Here’s a robust config_site.h snippet that covers the essentials:

#ifndef __CONFIG_SITE_H__
#define __CONFIG_SITE_H__

#define PJSUA_MAX_CALLS 256          // Your desired call limit
#define PJSUA_MAX_DIALOGS 300        // Should exceed call count (for early dialogs)
#define PJ_POOL_MAX_SIZE (2 * 1024 * 1024)  // Larger pools for more concurrent calls
#define PJ_IOQUEUE_MAX_HANDLES 512   // Scales with I/O operations per call
#define PJSUA_MAX_EVENTS 256         // For SIP events like presence (if used)

#endif /* __CONFIG_SITE_H__ */

3. Make Sure Asterisk Links to Your Custom PJSIP Build #

It’s easy to accidentally have Asterisk link to a system-wide PJSIP installation instead of your modified version. Fix this by:

• Pointing Asterisk to your custom PJSIP build during configuration:

./configure --with-pjproject=/path/to/your/pjsip/build/directory

• Verifying the linked libraries after compiling Asterisk:

ldd /usr/sbin/asterisk | grep pjsip

The output should show paths to your custom PJSIP libraries, not default system paths like /usr/lib/.

4. Check Asterisk’s Own PJSIP Configuration Limits #

Even if PJSIP is compiled for higher concurrency, Asterisk might enforce its own limits in pjsip.conf:

• Set global and endpoint-specific call limits:

[global]
max_concurrent_calls = 256

[your_endpoint]
type = endpoint
max_concurrent_calls = 256

Also, check asterisk.conf for the global maxcalls setting (though this applies to all Asterisk call types):

[options]
maxcalls = 512

5. Double-Check Your Compilation and Workflow #

Skipping a cleanup or install step is a common culprit. Follow this exact workflow:

1. Clean and recompile PJSIP:

cd /path/to/pjsip
make distclean
./configure
make dep && make
sudo make install

2. Clean and recompile Asterisk with the new PJSIP:

cd /path/to/asterisk
make distclean
./configure --with-pjproject=/path/to/your/pjsip/build
make
sudo make install
sudo make config

3. Restart Asterisk completely (a module reload won’t load new libraries):

sudo systemctl restart asterisk

6. Debug with Verbose PJSIP Logs #

Enable detailed logging to spot explicit errors when hitting the 32-call limit:

asterisk -rvvv
pjsip set logger on

Look for logs mentioning "call limit exceeded" or resource exhaustion—this can point to a missing configuration tweak you might have missed.

内容的提问来源于stack exchange，提问作者Wesley Schravendijk