The ability to add multiple phone numbers for different people, which can be used as an extension of your business (aside from being able to make calls) or even just personal use so you donβt have to carry around more than one number in case it gets lost/stolen etc.
Also they are generally cheap enough that I feel comfortable using them with clients/customers all over London without having expensive bills come through my account each month! Some features could do better like not requiringβ¦