S4,
Don't know about the freephone no but you may be able to if the phone has 0 level access.
You are correct about the comma and using BT chargecard may be a way.
Don't see why the police should object. Suggest a discrete call to your DATO office on stn.
When abroad, freephone no's may not work. Some providers have a roaming system. This involves dialing a local number for internet access. The costs vary from country to country - have a look on the BT website.
I managed some success in Bosnia dialing a UK access number through a mobile. Data rate very low 9600 baud as opposed to 56000 on normal telephone and v expensive! Only did it as an experiment.
Hope this helps a little.
GB