Incoming Calls get fax tone

I have an interesting problem and need help.
Here is the situation, i have a asterisk box from 3com. At my office when it is hooked to the analog line in the FXO port and a caller calls in they get a fax tone and no phones ring. This is the only device on the line and it is the asterisk generating the tone. The device works fine for calling out.

I have tested the box at 2 different locations and there it works fine, it is only at my office. I have tried putting filters on the phone line with no success. I have used a standard analog phone on this line and it works fine no issues.

I am just wondering if anyone else has ever had an issue like this. I am currently working with 3com level 3 developers to figure out what is going on but has had little success, but figured i would ask the real experts all you.

I am a network engineer so if there are any wild ideas out there let me know without worrying about me not being able to understand them.

Hi to all,
i’ve got the same problem…
I have configured my Asterisk server on a Linux machine, behind a linux firewall (port 5060, 5004, and from 10000 to 30000 - for test - redirected to my Asterisk server IP).

On my Asterisk, i’ve configured my VOIP account form EUTELIA, and when i do “sip show registry”, i get that i’m correctly registered!

I have also configurated two sip client (a phone GrandStream BudgeTone 100 and a softphone X-Lite). The internal work correctly, i can call the GrandStream form the X-Lite and viceversa… I also can call every external number form my softphone and from my GrandStream.

But when i try to call my telephone number, gived me by EUTELIA, from the external, i get the fax (or modem) tone, and no phones ring.

I’ve configured Asterisk thru the Asterisk-GUI interfaces, but i need to make some modify in the .conf files.

Here’s my SIP.CONF:

And here’s my USERS.CONF:

And here’s my EXTENSION.CONF:

Thanks to all for the help!!!