Yes it is a jazz network SIM code. 0300 is a jazz netweok code. This is the golden or unique number of jazz SIM. A special person takes this code. 0300-XXXXXXX. Every network have different code. Jazz network SIM codes starts from 0300 and end on 0309. ZONG network SIM codes starts from 0310 and ends on 0319. Warid network SIM code starts from 0320 and end on 0329. Ufone network SIM code starts from 0330 and end on 0339. Telenor network SIM code starts from 0340 and end on 0349.