Lync and LD Auth Codes

[Altayan]

When dialing a long distance number our provider prompts for a 4 digit authorization code for billing purposes. I cannot get Lync to send out the auth code and so we are unable to make LD calls. I have tested DTMF with off site IVR systems and that seems to work fine. I even called my mobile phone from Lync and I can hear the tones as I press the numbers in Lync. Is there something that keeps Lync from sending anything out until it sees a connected call? I have checked the DTMF settings on our PBX and they are set for 2833. I have gone through practically every setting I can find with our CO settings between our PBX and the Lync system and nothing seems to let me dial out the auth code. I've been all over google and worked with our support vendor, but no one seems to be having this trouble or know a solution. We are using an LG-iPECS 600 as our PBX and the auth codes work fine from those phones, so I am betting this is just a setting somewhere, just don't know where.