The council is lobbying a raft of telecoms firms with the aim of barring calls to numbers being used by prostitutes.
It has now met senior executives of telecoms firms such as One2One, Vodafone and Orange to lobby for a bar on prostitute lines.
The council has also sent telecoms firms and journalists examples of 'tart cards' with messages such as 'Actual school children read these cards'.
A Westminster spokesman said: 'These cards are an influence on young children - they have been trading them like Pokemon cards.'
In September last year, after two years of lobbying by Westminster, 'carding' became illegal. Since the change in the law, there have been 180 arrests and around 1.6 million cards seized.
This fresh lobbying push follows a successful targeting of BT earlier this year. The firm now operates a call bar on prostitute lines.