问题
Is it possible to restrict number of extensions created in asterisk using sip.conf when asterisk is using realtime tables.
回答1:
Asterisk not create extensions. It read extension from sip.conf, iax2.conf, realtime database etc
That files usually created by some web or control system(for example freepbx).
You should add restriction in your app/system which do add of extension.
There are no special limit on extensions number. Only limit like that is limit of concurrent channel count(controlled via asterisk.conf).
BUT asterisk is opensource soft. No any problem extend chan_sip, chan_iax2 etc to count extensions and load only first X extensions.
来源：https://stackoverflow.com/questions/38012168/asterisk-restriction-on-number-of-extensions