NOTICE: I am a ‘data guy’ by trade and experience, so beyond basic principles there may in fact be a much cheaper voice-centric device that can do this breakout for you. I am speaking in data lexicon that should mostly translate but may provide for major caveats in places. Read on:
There is no passive ‘adapter’ that is going to split out an E1 into 30 individual physical channels. E1 signalling by spec exists upon (2) TX pairs and (2) RX pairs. In order to time-divide this signal into it’s individual PHYSICAL 64K components you need to use a Mux, or a better search term would be “E1 Multiplexer”. I’ve not had to purchase equipment like this for some time so I cannot make any recommendations as to who makes the most economical or best price/performance ratio per device. For a long time I used mostly Adtran and Larscom equipment for TDM Muxing/De-Muxing. Solutions range from barely-adequate cheap devices up to enterprise-class switches that support e1/channel bank modules such as the Stratacom IGX/BPX. Anyway, search for ‘E1 Multiplexer’ and try combining that with ‘Adtran’ and ‘Larscom’ and see if that gets you closer. As far as an adapter… doesn’t exist… the device needs to perform TDM math to breakout the timeslots as well as identifying and routing each. Further, if your PBX can’t take a 64K digital signal and wants only 56K analog, you’ll also need a device that can perform A/D & D/A conversion. Price goes up. Keep a very close eye on your PBX line specs before investing in your mux so you don’t purchase the wrong gear.
It may be in your best interest to abandon that old PBX and install asterisk with an E1 card