Hi. Capitec supports this but Standard Bank requires the use of an account number for transfers made between Standard Bank account holders. If you must us a cell number, you can use Standard Bank's Instant Money service. But this will not be credited onto the recipient's account (even if they have an account with Standard Bank). It will be attached to the cell number alone until withdrawn.
Signature: I (as a co-founder of this site) have offered online support since 2014 but have now (as of Oct 2016) given up my shareholding and am now with http://www.saroms.co.za