A recent report by Anil Rao, Analyst and Glen Ragoonanan (pictured), Senior Analyst, Analysys Mason finds that "In 2012, communications service providers (CSPs) spent on SDP development to monetise the network investments they made in 2011. The top six suppliers in this market remained the same. Ericsson maintained its leadership of the SDP market in 2012, taking a 16% share of worldwide revenue. The top six suppliers – which also included Alcatel-Lucent, Amdocs, Huawei Technologies, Nokia Siemens Networks and Oracle – accounted for 61% of the revenue in the SDP market, which is consolidating as a result of acquisitions".
Infonetics recent report (here) claimed a $3.6B in 2012, with Oracle as a leader.
See "The service delivery platforms (SDP) market generated USD4.6 billion in revenue worldwide during 2012, up 7% from USD4.3 billion in 2011" - here.