*500 the number... could not be connected
 

I want to reach my voicemailbox by phone.
My voicemailbox is full; I did normally listen to the messages by e-mail.
Now I want to call *500 to empty all the messages; but then I hear:

The number you have dailed, could not be connected.

Question: what could be the problem of not reaching the voicemailbox by dailing *500? (For the rest my phone works fine)
Or, how else could I empty the current voicemailmessages?

Try dialing just 500 (no *). There's a chance that your ATA dialplan is interfering with dialing * ...

Alternatively from any regular landline or mobile call any local SipBroker Access number. At the prompt enter *010*500, then enter your 6 digit acct number and the 4 digit pin when asked...