It's actually really badly written that Plug n Talk softphone, as far as I can make out it hold the files open between events i.e. calls text messages or updating contacts etc.
So if you just unplug it you risk corrupting it, a lot of the time you will get away with it but eventually it will give up the ghost and need the delete/reinstall trick.
The software and original idea is from an Israeli company I believe, Smart just licensed the technology, the latest version of the software is much improved for example it can tunnel SIP traffic through a firewall even if the SIP port is blocked (like sky broadband routers are by default) this means that it can establish the Voice over IP connection even when otherwise intentionally blocked.
Long before it first appeared I had been trying to get a phone interface set up on my computer in the Phils so I could do exactly this over the internet but I never quite got all the bits together, just as well as it would have been a really wasted effort after the Plug n talk arrived a few years back
Roaming on any Philippine SIM is pointless, as although family back home can text you cheaply as you say it costs you loads to reply to them in the Phils.
As I always have a computer nearby I tend to receive text on the plug n talk and send text on Skype (3.5p each) even though it is more expensive Skype gives me delivery confirmation which you won't get with a phone or the plug n talk. Had a lot of reception issues with Smart in recent times so it is always good to know your message has been recieved
