Question about MWI on a ZAP channel


Hello all,

I was wondering if (and how) a person can enable the message waiting indicator on an analog phone (V-Tech cordless model vt5831) that is connected to a TDM400p? If it’s possible what lines do I need to add to what files? The base station has a message light and it would be nice if I could get the lamp to light up when there are messages.

Any help will be greatly appreciated!




most consumer phones like that that have mwi lights will listen to the stutter tone to determine if the led should be on or off. On my ATAs (Sipura) they will play a stutter tone when there is a message. I haven’t used any zap FXS channels so I don’t know if you can do that. If you can set the dial tone to a stutter tone when voicemails are there, then that would do it. (The phone typically picks up and listens to the line shortly after it receives an un answered phone call or after it has been off hook, to determine if a message came in or was deleted so it can change the state.




Thanks for the response! For some reason * doesn’t seem to be sending the stutter tone to the phone. I guess I’ll have to do a little more digging in the logs to see if I can figure out why :smile:. Do you have any idea what the log entry for sending a stutter tone would look like?

Thanks again,



you will have to set the

mailbox = 1234@context

in the zapata.conf for that channel to get the stutter tone

more info on it here … apata.conf


Hi Rusty,

Thanks for the reply! I have mailbox = 1234@device (or should the context be from-internal?) in the zapata.conf file , still no joy. I even tried adding the adsi=yes even though the wiki says you don’t need it anymore, still no joy. Maybe it’s my phone. I’ll try anotherone when I get home from wotk.




It is refering to the context the mailbox is in in the voicemail.conf. If its in the default context in voicemail.conf you just need the mailbox = number and not the @context part

if there is a message waiting and you lift the hanadset you should be able to hear the stutter on the phone


Hi Rusty,

Does it matter if it is mailbox=1234 (no spaces) or maibox = 1234 (with spaces)?




I believe but not 100% postitive if you are running 1.2 and above it doesnt matter anything before that required spaces.


Yep, removing the @context part seems to have fixed it. It’s working great now. Thanks for all the help!