Yealink t18p issues when dialing a vendor with IVR

Hi Everyone,

I needed some cheap phones to implement pbxiaf and I found the t18p for $50. Everything is working fine except for one weird thing:

When my users dial certain vendors that use an ivr/autoattendant, the numbers pressed are not recognized. For example press 1 for english 2 for spanish, my user presses 2 and nothing happens. It seems that the tone is awfully short. Anyone ran into that before? I have linksys spa941 phones and that works great. It also works fine on a softphone. It only happens with a handful of vendors. I have changed or verified the following settings on the phone itself:
Phone>tone> set to united states (I believe this controls the frequency of the tone)
Phone>features>General Information>Key As Send>disabled (this feature allows the phone to retain any numbers pressed after the call is made and send them only after the user presses #).