Having an usually issue with an ASA 5505 that has been up and working for a number of years. Installing 25 VOIP phones on the LAN connecting to a hosted VOIP provider on the internet. We have disabled SIP inspection but we can only get 19 phones to come up and register with the provider, while the other six will not register. If we unplug or power down one working phone then one of the other 6 non-working phones will register and come live. If we power up the unit we just powered down, that phone then becomes part of the 6 that will not register with the VOIP provider. I installed my test Fortigate FW and all phones come up and register fine. I'm at a loss. It appears as if there is some sort of connection limit of 19 but I can't find in the config nor I can find anything related to this online. The unit is running IOS 8.2(5). Has anyone else had this issue and would know the resolve? Any help will be appreciated. Attached is a copy of the ASA config.
