[Users] What Media Gateway (connected via SS7) do you use

Hello everyone, At first I am sorry that this is slightly off topic. I am doing some research for my company (which does not want to be named therefore the gmail. I am sorry for that) which carrier grade media-Gateways are used by others to connect their SER (or any other SIP-Proxy, - Router, -PBX, etc.) to the PSTN. We are currently looking for something that can be connected via SS7 in Europe, scales good (i.e. starting with 4-E1s, but with no limits to add more) and supports * SIP ;) * G711, G723 and G729 A/B Codecs * Echo Cancellation * VAD * CNG * T.38 * Modem Bypass * DTMF-Transmission using RFC2833 or In band (for G711) and preferably even SIP-INFO I would love to hear which system you use/prefer and what your experiences are ( i.e. would you buy the system you use a second time) and if I forgot something in my requirements that in your eyes is crucial. If you don't want to/can name your company that's fine with me (as I can't either), I just need some opinions. Bye, K