New VOIPo user - a few issues

[Belinrahs]

I just received my Grandstream HandyTone 502 in the mail today and I've set it up. So far calls sound good. But I've run into a couple issues so far.
{FIXED}1. When I dial 123 to check voicemail, the automated system does not seem to receive any keypresses I make. I have confirmed this issue with more than 1 phone. Other phone numbers I call are able to receive my keypresses - for example, if I call my GV phone number, press * then my PIN to check voicemails, that works fine.{FIXED}

2. I'm trying to figure out how to make QoS work - where if I'm downloading a file or something, and I want to make a phone call/answer the phone, the internet connection isn't being overtaken by the download so I can't use my phone. I have tried Modem -> Grandstream -> Router, and Modem -> Router (with QoS configured and SPI firewall off) -> Grandstream, and the former works better but still will have problems. Could any of you provide insight and possibly how to configure this to work? My router is a Linksys WRT160N running DD-WRT firmware.