The following solution showed the Nokia 6700 classic RF circuit. You can used this as a guide to troubleshoot no network problem on the device.
Nokia 6700c classic No Network Signal Solution
In troubleshooting network problem on Nokia 6700 classic , you must first check the RF power supply chip. Then, the RF clock (VXO) then down to the corresponding PA (power amplifier chip). There are two PA's is mounted on it, for GSM and WCDMA bandwidth. Before trying to rework or replace the chips ensure that each corresponding supply voltage were okay.