Nokia 3600/3650

The Nokia 3600/3650 (triband GSM 850/1800/1900 MHz) was the first Symbian Series 60 smartphone to appear in American markets. It was also the first phone with an integrated camera delivered to North America.[2]
One of the common complaints of the 3600/3650 was its unique circular keypad. Many owners wanted a Series 60 device with a conventional keypad, however some stated that the rotary style keypad made text messaging easier and faster.
The Nokia 3600 and 3650 was replaced with the Nokia 3620 (GSM 850/1900) and the Nokia 3660 (GSM 900/1800/1900) respectively, both of which feature a conventional keypad and an improved 16-bit color display.

The Nokia 3620 and 3660 are successors of the Nokia 3650 smartphone. Both run on Nokia Series 60 version 1.x (and the Symbian operating system).
Changes from the 3600/3650 include a conventional keypad (as opposed to the 3650's circular keypad [1]), and a 16-bit display (as opposed to the 3650's 12-bit display).
Both are basically the same phone, except that the Nokia 3620, being targeted at the US market, operates on GSM 850/1900, while the Nokia 3660, a European phone, operates on GSM 900/1800/1900.
Both of them use an ARM compatible main CPU (ARM4T architecture) running at 104 MHz.
In the United States, the 3620 was carried by AT&T Wireless and Dobson Communications, while the 3660 was carried by T-Mobile USA.
The replacement for the Nokia 3660 is the Nokia 3230. The 3620 does not have an official replacement, although it was replaced by the Nokia 6620 in AT&T/Cingular's lineup after the merger between AT&T Wireless and Cingular.