PVC tape on telephone cable joint.

Hello All,

PVC tape works fine on a twisted electric cable joint. But Recently when I used same tape on a telephone cable (well twisted joint) it corroded the whole joint in few days and infact it elated whole joint, cable was observed tarnished up to deep inside of covering.

I did this 3times and same results observed.

finaly I put same tape on a screwed joint at the same point and this time it works fine.

Does it have to do something with riding high frequencies?

valuable inputs of members are requested.