Transmitting E1 or serial data streams over traditional PDH or SDH networks is outdated. These days, IP is used to transmit this type of signals.
The benefits of IP are apparent: in most cases only one network remains to be managed and most times the IP network has enough resources available. Also, cost efficiency is apparent since expensive leased lines can be done without.
RAD Data Communications invented TDMoIP technique. From 1999 on, this Israeli company has provided its TDMoIP solution called IPmux. TDMoIP then was patented by RAD. In respons to this, CESoIP and Satop were developed and standardized by other vendors. Of course, RAD's IPMux and Gmux devices support these standards.
Also, RAD developed a new product named MiTOP: a 1 channel E1 or E3 to IP device in SFP (small form-factor pluggable) version. MiTOP may be plugged into existing Ethernet switches by e.g. Cisco, Alcatel-Lucent.