This Counter32 tracks the total attempts to upspeed voice connections over bearer PVC connections that were rejected by port-level CAC. Upspeed failures specifically indicate that fax/modem tone-triggered bandwidth increase requests are being denied due to insufficient bandwidth, which can degrade fax transmission quality on the affected calls. An engineer troubleshooting frequent fax failures over VoIP trunks would check this counter to see if upspeed rejections, rather than line noise, are the underlying cause.