Archived:CTelephony::DialNewCall() API gives connection error in dual mode (Known Issue)
After programmatically hanging up an outgoing call created by the user or by another application, (using, for example, CPhCltCommandHandler::Chup() or the Phone Client API), an attempt to create a new call with CTelephony:DialNewCall() may fail.
When the device is in a 3G network and a new call is established immediately after the previous call has been terminated, call creation may fail with the telephony application displaying a Disconnected note. Note that this behavior has only been observed in 3G networks when using a device in 2/3G dual mode.
No known solutions for 3G (dual) network mode, however adding a delay between hangup and call creation increases the success rate. It has been also observed that new firmware versions do not have this problem anymore; for example, the issue cannot be reproduced with Nokia N95 sw v20.0.015.