Modem Equivalent

I am working on a revamp project. The old RTUs have built-in FSK modems with the following specs:

1. Mode: Half Duplex
2. Data Rate: 1200 BPS asynchronous
3. Data Bits: 8
4. Parity: None
5. Modulation: FSK
6. Carrier Frequency: 1200 Hz, Space 2200 Hz.
7. Input Impedence: 20 Kile Ohm unbalanced
8. Output Impedence: 600 Ohm balanced
9. RTS to Transmission Delay: 10 ms
10. Sensitivity: -35 dB
11. PTT signal: Isolated, solid state switch

Can anyone suggest to me a modem that I can use which has the above mentioned specifications?

Guys I need this quick.

Thanks in advance.

The MARC 366-101 matches most of the specifications you list. The major differences are that we only spec down to -25 dB and the PTT output is a contact closure. You did not specify the power requirement but our modems are 24 VDC powered. Link to a data sheet here:
http://www.miille.com/din366-101.pdf

and the manual here:
http://www.miille.com/366101_Users_Manual_Rev_2.pdf

My contact information is on the data sheet.

Thanks,

Jerry Miille
Miille Applied Research Co., Inc
http://www.miille.com/

From those specs, I think the old RTUs have Bell 202T leased-line telemetry modems. I've used these in systems which had one master site and several remote sites. We tried several before settling on the Control Microsystems model 5902. The 5902SAF version has a 120vac adapter and a full-duplex adapter board that keys the carrier on data instead of using the RTS/CTS lines in the RS-232 port.