The E1 service card is a type of multiplexing structure used on the STN6200 platform that supports 21 x E1 service access and maps E1 to any of the 63 x VC12 in STM1. It can be combined with the service card to converge to OTU1 or OTU2 services.
E1 Service Card
E1 Service Card for STN6200 series