Because the English "short A" sound does not exist in German, so Germans "can't hear" that sound -- it sounds to them like the German "short ä" sound instead.
(I'm sure you've had the opposite happen, where you "couldn't hear" certain German sounds -- for example, many seem to find it hard to distinguish between ihr and er.)
So Germans pronounce that word with a German "short ä" sound.
Similarly with other English loanwords that feature the English "short a" sound, e.g. die Band (musical band) sounds like "dee bent" rather than "dee bant" or "dee band".
Ahh, I see. The "short A" sound in question I suppose is /æ/ then? It's interesting, because in my dialect of English I pronounce that sound /a/, but exposure to /æ/ must have made me effectively hear /æ/ as /a/* I find it interesting that Germans perceive the sound as closer to /ɛ/.
About ihr and er, I'm not really sure what you mean since ihr and er sound like "ear" and "air" to me; which from the start sounded completely different to me. I did however find "ü" vs "u" difficult (though I've learnt to both hear and speak the difference), and also find it difficult to distinguish between "herr" and "her", and other short vs. long vowels before 'r'.
(*In case you're wondering how I know I say /a/ if I can't hear the difference, I know because I can feel where my tongue is)
"This phone is not portable." ( since "Handy" is obviously a made-up word to denote that it is hand-held. ) But aren't most phones hand-held? Then there are corded and cordless models of land-lines also. Lots of things are <handy> but I guess <Handy> is reserved for cellular phones!
Handy is a noun, not an adjective. It means "mobile phone" or "cell-phone".
(I've heard that it comes from "Handy-Talkie", which was apparently the brand name for a very early model of portable telephone, or at least portable radio transmitter.)
So ist kein Handy means "is not a mobile phone".
(It does not refer to a cordless landline phone. That would be ein schnurloses Telefon. German makes a similar distinction to English between schnurlos "cordless" and drahtlos "wireless".)
In Switzerland, a mobile phone may be called Natel, after the brand name of an early mobile phone provider.