Voicemail Problem (incorrect login, password?)

I am having a strange problem.
Asterisk v1.8.7.0
Grandstream GXP285 (ulaw)
X-Lite 4.1 build 63214 (ulaw)

When dialing *97 from the X-Lite softphone, Asterisk accepts the password and allows entry into the voicemail system.

When dialing *97 from the Grandstream phone, the password is not accepted. The incorrect login, password prompt is played.

When viewed from the console, the following is displayed:
– Incorrect password ‘’ for user ‘445’ (context = default)
– <SIP/445-0000002c> Playing ‘vm-incorrect.ulaw’ (language ‘en’)
– <SIP/445-0000002c> Playing ‘vm-password.ulaw’ (language ‘en’)
– Incorrect password ‘’ for user ‘445’ (context = default)

I am not sure it it is an Asterisk/FreePBX config, or a Grandstream config.

Has anyone else seen this?

I’m using Grandstream GXP2000 and GXP2020 SIP phones. I had two voicemail problems, the “MSG” or voicemail button wouldn’t do anything. I found the solution on this board: set “Voice Mail UserID” in the browser-based config page under “Account 1” to *97. But some extensions could access the voicemail from the phone, but not others. I could log in with the same password from FreePBX’s main menu (“Voicemail & Recordings”), but not from the extension.

I found a simple solution after trying multiple exasperating steps: some extensions were set to send DTMF “in audio” rather than “via RTP (RFC2833)”. Once I set them to send DTMF via RTP/RFC2833, problem solved!

I hope this helps someone, because this has been driving me crazy for weeks.