The persistent DDR circuit was introduced in IOS version 12.2. You can find more information on this feature at http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122t/122t11/ftdperst.htm.
The complete Dial Technologies Configuration Guide appears at http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/dial_vcg.htm.
The persistent DDR circuit was introduced in IOS version 12.2. You can find more information on this feature at http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122t/122t11/ftdperst.htm.