Clear-Com stopped selling the CAM-IF product  in Jan 2012 The CAM-IF was used to sum a number of camera talkback circuits into one 4-wire on the matrix.
Most systems have individual 4-wire feeds to the Camera CCU - so for an 8 camera OB this will use 8 ports on the matrix Some customers to save on port space would sum all the cameras CCUs to one port by using the CAM-IF unit
The CAM-IF was  2RU unit that was made up of 2 x 1RU products 1RU Mixer  provided 8 mono into 1 mono 1RU DA provided 1 mono to 8 mono outputs

This was a 3rd party product, the unit is still made by the original manufacturer (Audionics UK) or alternative mixer / DA units can be sources locally from your country.

There are a number of mixer / DA products on the market and we recommend you source a local manufacturer.  However you can look at using:

Glensoud DA : https://www.glensound.co.uk/products/distribution-amplifiers/ (Signature ADA 1:8G)

Behringer https://www.behringer.com/product.html?modelCode=P0CCU (MX882)
 
Glensound DA/MIXER - GS-TBMM001

Kramer Electronics DA - VM-1110Xl

Kramer Electronics MIXER - VA-15XL

CPT Systems : 

• ADA126 https://www.ctpsystems.co.uk/das.html  & 

• Mix2 https://www.ctpsystems.co.uk/mixers.html