How to decode sms spam from telecom operator ?...

[a a]

Not sure why telecom is using fake coding in sending sms messages

examples:

1. +Pyzvt2Pvp9=ΔΞΣWÆP#!ΔT......
2. +Δ2wt:ΔYÆΨΣÆΨ...
3. +Δ2wtYΣΨXΨΘΣΘΘPyu7...
4. ΘΣP#!P;Δ8y2ñ2wqt2Δz2y....

some sms messages are sent as ASCII
and some as fake as above

any idea, why telecoms play so badly ?

If I know the encoder/algorithm,
I can send such encoded Merry Christmas messages to telecom operator