Telephone number string length in platformRequest is limited on Series 40 (Known Issue)
The telephone number string (including the post-dial DTMF tones) is limited to 30 digits on certain Series 40 devices.
The MIDlet.platformRequest(String) method call can be used to initiate a phone call using the "tel:<number>" string as the parameter. The telephone number can also contain post-dial DTMF tones.
The length of this string is limited on certain Series 40 devices.
There is no workaround available.