New IAX2 Security Enhancements Not Yet Supported by Majority of IP Phones
Starting with Asterisk 18.104.22.168 the IAX2 implementation has some strong security enhancements. Unfortunately, these enhancements are not currently supported by the majority of third party IAX2 soft and hard IP phones. As a result of these enhancements, after an Asterisk upgrade these IP phones unexpectedly stop communicating.
For example, the Iaxmodem cannot register on Asterisk and as a result the Elastix fax2mail service does not work anymore. Communication with the popular IAX2 softphone Zoiper is also affected. According to the Digium IAX2-security.pdf:
"... to bypass the security enhancements completely and have Asterisk work exactly as it did before, the following options can be specified in the [general] section of iax.conf:
calltokenoptional = 0.0.0.0/0.0.0.0
maxcallnumbers = 16382
To apply the workaround for the Xorcom XR1000/XR2000/XR3000 IP-PBX, the parameters mentioned above must be defined in the /etc/asterisk/iax_general_custom.conf