Problems making call with Snom phones after upgraded to 8.4.18 (Firmware 8)
After a little research i found that disables RTP Encryption make my outgoing call work again.
The problems with dialing a number was happen after upgraded to 8.4.18.
Go to the webpage of the phone, click on identity 1, click RTP and set RTP Encryption to off.
This seam to be a problem on Snom 300, Snom 320, Snom 360, Snom 370