The intelafone website has an unboxing video of a landline ATA that they supply. At 21 seconds into that video when the ATA is put down at the bottom of the screen it is just possible to discern the word "Grandstream" in the same style as Grandstream use. It looks like the device is a Grandstream HandyTone HT701
http://www.grandstream.com/index.php/products/ip-voice-telephony/consumer-analog-telephone-adaptors/ht701.
Watching the video for the business system it is even easier to see that they are Grandstream GXP1400/1405 phones. So, almost certainly intelafone is using standard SIP protocol and the OBi products could be configured to support it if you could ascertain the account parameters.