Apple has released detailed support information explaining the differences between iPhone calling features on the AT&T and Verizon networks. Because AT&T Mobility uses GSM technology and Verizon Wireless has a CDMA network, each iPhone 4 has different calling capabilities. Recently it was revealed that Verizon's network suffers from conference calling limitations, but there are other differences as well. The table below was released by Apple to illustrate the details.
Several differences between the Verizon and AT&T iPhone 4 have already been revealed, including changes in the antenna design and other components. What might surprise some people are actual differences in calling capabilities between the two devices. It's not clear whether or not these differences in functionality are due to Verizon's network technology or some other reason, however business users will especially be interested in these calling limitations.
Unlike the AT&T iPhone 4 pictured at left, the Verizon iPhone 4 doesn't allow users to swap between calls on hold when adding calls to a conference. In fact, both calls pictured here are simultaneously connected and must be hung up together on the Verizon iPhone. In contrast, the AT&T user can switch between calls or join them together to create a conference call.
UPDATE: You can easily delete an individual call on your Recents list by swiping left on the call you want to remove. This will bring up a large red Delete button. Just tap the button and the call will be removed from the list.
Deleting the entire iPhone calling history is simple, just touch the Clear button in the upper right hand corner. Sometimes you'd rather delete just one phone number from the list.
Many iPhone owners expect that incoming call blocking is a built-in feature of the iPhone. Unfortunately, this is not the case. Such a feature is controlled at the provider level. Furthermore, most providers fail to offer call blocking to their customers. Providers that do often charge an exorbitant rate for this feature, such as AT&T in the US which offers a service called "Smart Limits" which includes call blocking but comes at a pricey $5 per month.
There are a couple solutions/workarounds that you can implement:
The iPhone will only go blank if you deliberately press the sleep button to shut off the screen during your call, or if you trigger the proximity sensor. The proximity sensor is designed to turn off the screen during a call if the iPhone is close to your ear. This prevents accidental pressing of buttons on the screen and saves the battery, as well as keeping your ear cool.