I've been struggling with this issue for some time now, and now trying this forum for some help.
We run a yeastar s300 pbx.
We have about 200 SNOM300 phones working good.
My problem is with the newer SNOM phones. IO and D305 phones.
For some reason the phones doesn't accept the pin codes entered for voicemails or even pins for outbound calls.
You can enter the pin, but it's like the PBX doesn't recognize the keys pressed or it doesn't receive the keys pressed.