There are many used 1st Gen Adtran Total Access 900 Series Gateways out there at much lower prices than the 2nd Gen.
I was curious if there are major differences between the two units.
After some research I found the following:
| Feature | 1st Gen | 2nd Gen |
| 3 Way Conferences via FXS users | 0 | 3 |
| Max TDM to IP Call | 24 | 30 |
| Max T.38 Sessions | 1 | 4 |
| Echo-tail Length | 16 ms | 64 ms |
| Supports MGCP | No | Yes |
| Flash Memory | 32MB | 64MB |
Based upon Echo-tail length increased to 64ms and the increased number of T.38 faxes I stick to the the 2ng Gen Gateways.
VoIP4EA 