Isn't it very typical for an ISP to run their line onto your premises and put the demarcation device on your premises with your power supply etc? Usually there
isn't a "their side" where it still works. It's your premises, then up to kilometers of wiring, then the central exchange. Equipment required to terminate the wiring at your end obvious has to be at your end, not theirs.
It's possible that the termination equipment could be a bare SFP and not a big box, but the ISP wants to be able to monitor the status of your connection up to the termination equipment, because that is their responsibility to keep online, and they can't do that if it's just an off-the-shelf SFP. They probably wouldn't agree to do it and still have any SLA.
If there's a physical problem with the box (too big/loud) you can try negotiate for a different box but if you just want control over your network, sorry but that just isn't how it works. Your network starts at the demarcation, and you don't want to be responsible for speaking whatever protocols the ISP is using internally, either. Up to the demarcation, it's ISP internal network, and past that, it's your network, with a standard handover interface like Ethernet.
It's possible that the termination equipment could be a bare SFP and not a big box, but the ISP wants to be able to monitor the status of your connection up to the termination equipment, because that is their responsibility to keep online, and they can't do that if it's just an off-the-shelf SFP. They probably wouldn't agree to do it and still have any SLA.
If there's a physical problem with the box (too big/loud) you can try negotiate for a different box but if you just want control over your network, sorry but that just isn't how it works. Your network starts at the demarcation, and you don't want to be responsible for speaking whatever protocols the ISP is using internally, either. Up to the demarcation, it's ISP internal network, and past that, it's your network, with a standard handover interface like Ethernet.