Early reports and tweets from Verizon Wireless support staff suggested that simultaneous data usage and voice calls would be possible on the new LTE-equipped iPhone 5. A new statement says that's not in fact the case: taking a call on the iPhone 5 will cause the handset to drop any data connection.

The support person tweeted yesterday that "You can run voice/data at the same time on 4G devices, while in a 4G area!" when asked if the 4G iPhone 5 would permit simultaneous voice and data. Today, however, AllThingsD noted there was no simultaneous voice and data after all. We asked Verizon and were told "iPhone 5 was designed to allow simultaneous voice calling on the Verizon Wireless network while browsing the Internet over WiFi. This is no different from the current iPhone 4S. For further details, check with Apple."

A long-standing feature of the CDMA networks used by Verizon and Sprint is they don't permit simultaneous use of a data connection and a voice connection. Due to their use of the data-only EVDO standard (instead of the data plus voice EVDV alternative), any inbound or outbound call forces the phone to drop the data connection and revert to a CDMA connection.

In some regards, LTE is no different. Voice over LTE (VoLTE) is coming, eventually (the first commercial rollout started last month in South Korea and MetroPCS in parts of the US), but as of right now, there's no way to route a voice call over LTE on either Verizon or Sprint. However, all of Verizon's other 4G phones can connect to the CDMA network, for calls, and the LTE network, for data, simultaneously. This allows concurrent usage of voice and data, albeit over two separate network connections with two separate antennas. Some of them can do a similar trick with EVDO and CDMA, using two antennas to connect to both networks concurrently (a feature called SVDO).

iPhone 5, however, lacks this ability to connect to the legacy voice network and LTE network simultaneously, forcing the choice: data or voice, but not both.

This could explain the Verizon rep's error; every LTE handset currently available on the network can use voice and data, and he assumed that the forthcoming iPhone 5 was no exception.

The inability to use LTE with any other cellular connection also strikes AT&T's handsets, but is much less significant there: on AT&T, the iPhone 5 can fall back to HSPA+, and HSPA+ does support simultaneous voice and data. You won't get full LTE speeds when on a voice call, but you'll still be able to make searches, get directions, check for e-mails, and anything else that requires a data connection.

As for why the iPhone 5 doesn't support simultaneous CDMA and LTE connections (in contrast to competing Android products), we've reached out to Apple for details. At the time of writing, we are awaiting a response. In lieu of an official answer, we would speculate that it is a limitation of iPhone 5's "dynamic antenna," and that can't be tuned simultaneously to all the frequencies it would need to support simultaneous CDMA and LTE connectivity (other handsets include multiple antennas to support multiple cellular connections).

Update: The New York Times is reporting the same theory; the iPhone 5 would need an additional antenna to allow connection to CDMA and LTE networks simultaneously.