When viewing both phones, you'd be hard-pressed to notice any real design differences between the Z520a and the Z525a. Both handsets have identical dimensions (3.2 by 1.8 by 0.9 inches; 3.3 grams) and bear the same blue removable faceplate (other colors are available), looped antennas, and rear-facing speaker. The camera lens is located just below the one-inch diagonal (101x180 pixels), 4,096-color external display, though it's disappointing that Sony Ericsson still left out a flash.
There's one major difference on the outside of the phone, however. Instead of the Z520a's camera shutter being on the left spine, the Z525a has a PTT button there. Though that means there's no dedicated camera key on the phone's exterior, we don't mind because many users reported problems with the Z520a's camera control. Because it's not lockable, a lot of people were taking pictures of the inside of their purse or pocket. The volume rocker and the infrared port sit below the PTT button; we like that you can access calendar appointments with the PTT button when the phone is closed.
The interior of the Z525a shows no changes from its predecessor. You'll see the same 1.8-inch (128x160 pixels) main display with support for 65,530 colors. The menu interface, navigation controls, and keypad buttons are alike as well (see the Z520a review for a full description). Here again, we're glad to see this good keypad from Sony Ericsson.
The Z525a incorporates features from the Z520a, with a few changes. The 500-contact phone book is too small, but you can save an additional 250 names on the SIM card. This time, however, you get only 13 (40-chord) ring tones instead of the Z520a's 46 choices. On the other hand, the simple digital music support means you can download additional tunes from Cingular via the WAP 2.0 wireless Web browser. Other features include a vibrate mode, an alarm clock, a world clock, a calculator, a stopwatch, a timer, a notepad, PC syncing for your contacts, a tasks list, a calendar, text and multimedia messaging, a code memo for storing sensitive information, a speakerphone, a voice recorder, an infrared port, a wireless business-card exchange, POP3 and IMAP4 e-mail support, and Bluetooth for calls and file transfers. And of course, the Z525a offers support for Cingular's PTT network.