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.
Like on the Z520a, the VGA-resolution digital camera on the Z525a comes with plenty of features, but we weren't quite pleased with the end result. You can take pictures in 640x480, 320x240, and 160x120 resolutions, as well as Normal and Fine quality settings. Other image options include Normal, Panorama, Frames, and Burst shooting modes; Black And White and Sepia picture effects; a night mode; a self-timer; a 4X zoom; and a brightness adjuster. The video recorder takes clips with sound, with clip length limited by available memory. Editing options are similar to those of the still camera. When finished with your shots or videos, you can send them in a multimedia message or save them to the phone's memory. Yet in an unwelcome change from the Z520a, the Z525a offers 12MB of shared space instead of 16MB. Also, while we were hoping for better photo quality on the new phone, images showed little improvement from the Z525a. Photos were equally washed out and grainy, and the lack of a flash didn't help. But if you care to play, PhotoDJ and VideoDJ applications are available.
You can personalize the phone with a variety of wallpapers, color themes, screensavers, and sounds. If you want more options, you can download them from Cingular and compose your own ring tones with the Music DJ application. Gamers can enjoy demo versions of four Java (J2ME) titles: Asphalt: Urban GT 3D, Tetris, Yahtzee Deluxe, and NY Nights. You'll have to buy the full versions.
We tested the quad-band (GSM 850/900/1800/1900) Sony Ericsson Z525a world phone in San Francisco using Cingular Wireless service. Call quality was on a par with the Z520a, which is to say it was good overall with acceptable clarity and loud volume. The phone picked up wind noise easily, and callers had more trouble hearing us than on the Z520a. Though it wasn't a big problem, generally we had to repeat ourselves several times when talking to an automated voice-response system. This was true even when we were in a quiet location. The rear-facing speakerphone was surprisingly loud; it's best that you face the speaker up if resting the Z525a on a surface. You must place a call before you can activate the speakerphone, but it doesn't hang up automatically when you close the flip. When we tried a Bluetooth headset, call quality didn't suffer significantly.
The Sony Ericsson Z525a promises less battery life than its predecessor. The rated talk time is 5 hours (instead of 9). Our tests confirmed these results with 4 hours and 55 minutes of talk time. The promised standby time is 16 days (instead of 13). According to FCC radiation tests, the Sony Ericsson Z525a has a digital SAR rating of 1.47 watts per kilogram.