Casio B430 - Manual (Page 15)

GETTING STARTED
14 Binatone Help Line: 0845 345 9677 (for UK only. Local Call rate)
NOTE:
At least four GPS signals are required for the PND to function .
There may be occasions within your home or surrounding area when the
signal strength is limited and GPS navigation Mode may not be possible.
This is quite normal of products of this type.
Additional maps and upgrades:
Please visit www.binatonegps.com or contact the helpline on 08452 459677 for
more information.