Unfortunately couldn’t test I2C Master/Slave communication between 2 Pic 16F268 due to lack of hardware capabilities! The 16F628 doesn’t have SSP module and so can not support I2C protocol by hardware. I have tested I2C Master by software when communicating between Pic Master and Dallas DS1721 ‘2-Wire Digital Thermometer and Thermostat’ Slave. It worked fine, but I really need the full capability of I2C Slave by hardware (Interrupt Routine) and at this moment have only emulated the Master side! Also would like to leave my code small and clean!
I have now found alternative Pic with SPP (I2C by Hardware) support - PIC 16F690 I/P . Still searching for this device on local electronic stores, but no luck yet! Better to order from Internet 
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While waiting for the new Pics I will try to make some more advanced tests.