Your Saphe traffic alarm can be paired with as many phones as it suits you, and your phone can be paired with as many Saphe devices as the phone has memory to store information on.
One traffic alarm and one phone at a time
Although you can pair multiple devices, a phone can only be connected to one traffic alarm at a time, and a traffic alarm can only be connected to one phone at a time. This means that your phone will not be able to be connected to several Saphe traffic alarms in your car at the same time. In that case, you need a phone for each, but it can be paired for them, so you just need to turn off the one you do not want to use, and then you phone will connect, to the one that is on.
Likewise, more that one person can not be connected to the same Saphe at the same time, but if there are several who share it, everyone can have their phones paired to the same Saphe, and then everyone will be able to use it when they drive - given that they have their phone with them, and it is paired with the Saphe device.