GAP Compatibility is essentially an agreement between the different phone manufacturers to make their DECT cordless handsets work with one an other.
For example: You have a GAP Compatible BT Diverse system which is nearly 10 years old, but one of your handsets has been dropped and won’t work any more – you like your BT Diverse and don’t want to replace the whole system, but the same handsets aren’t available any more. With GAP you could purchase any additional GAP compatible handset regardless of the manufacturer (Panasonic, Siemens, BT etc) and register it to your existing BT Diverse system. Saving you the cost and hassle of replacing all of your phones.
Things to note: Gap Compatibility ensures that the handset will register to your existing base unit and will make and receive calls – other functions such as call transfer, caller ID, phonebook transfer etc are not guaranteed to work due to software on different handsets and manufacturers being different. Due to the thousands of possible combinations of handsets available, this is not something anyone could advise on without testing the exact units together, however it is more likely that like-for-like manufacturer handsets will allow these features to work.
PMC Telecom stock a wide range of GAP Compatible additional cordless handsets on our website here.