I just discovered a very interesting aspect of the P310 phone: The voicemail button works opposite the way I’m used to it working. You press the voicemail button WITHOUT dial tone. Thus, (a) you press it while the handset is on-hook (in which case, the speakerphone turns on), or (b) you press it while the handset is off-hook, but AFTER you’ve pressed “Cancel,” so there is no dial tone. In other words, the voicemail button works only if the phone has not yet been picked up. This makes sense, if the phone has a visual voicemail app that displays a list of voice messages on the phone’s screen. However, according to this post, the P310 and P315 phones do not have visual voicemail apps. (That also explains why the template option Voicemail Key Type values “Voicemail Application” and “Standard Voicemail” both produce the same result.)
As I noted, I’m used to getting dial tone before pressing the voicemail button. That is how it works on my Grandstream phones (GXP2130 and GXP1625), and the way I remember other IP phones working, although I admit I’m referring mostly to IP phones I used many years ago.
So, my problem was caused by my misunderstanding the way the Sangoma phones are designed to operate, and my P310 is not malfunctioning. I’m sorry about my confusion, although I suggest the templates for phones without visual voicemail apps should not imply that the Voicemail Key Type value influences how the phones treat their voicemail buttons.
Thanks,
George