Fun and games with VOIP

I changed my phone over from BT Broadband Voice to Sipgate.  This entailed some fuss, including upgrading the BIOS in the ATA186 VOIP box that BT gave me, and then tweaking settings by hand.  It all seems to work though, and I now have a new home phone number(in the usual place in my userinfo now).

The only problem I'm having is that my touch-tone phone seems to have stopped sending recognisable digits.  However, I can't tell if this is a problem with the service, if the phone went wrong, or if the number I was calling was just having problems.

Anyone got a phone number for somewhere I can test the touchtones with?  Even some bank that requires you to navigate around their system using your phone would be handy...