It is worst mistake of my life, that I bought Samsung galaxy core from shop on 13k.It is work like a china.
Drawback of Samsung:-
1) Main fun of mobile is to make a call from anywhere but Samsung mobile loose the network/tower , even my old Nokia n72 shows same operator network at same place.
2) Samsung give slow response to incoming call i.e. waiting for long time to connect.
3) Touch response become weak day by day.
4) It does not have cancel button/icon on second stage of dialed number ,which make voucher recharge difficult, or make incorrect input to customer call.
5) It support only 720P i.e. it does not support full HD.
6) Video recording does not support zoom function & recording is at 720p but still have black color in recording as compare to image capture. Screen vision always changing black to white and white to black vice versa.
7) Some time screen get black or dim after charging which need to make a restart to mobile to come to original.
8) (It does not have light sensor)Display does not glow many time after you remove it from ear which make call disconnect impossible still you remove the battery, as switch off or restart does not work at that time & call is connected so billing increases.
9) Net speed is too slow though it having 1.2Gz processor and 1GB RAM.
10) I am using inbuilt ringtone ,still it is having very low sound & does not come to know easily in traffic or T.V sound.

In reply to the review
< It is worst mistake of my life, that I bought Samsung galaxy core from shop on 13k.It is work like a china. Drawback of Samsung:- 1) Main fun of mobile is to make a call from anywhere but Samsung mobile loose the network/tower , even my old Nokia n72 shows same operator network at same place. 2) Samsung give slow response to incoming call i.e. waiting for long time to connect. 3) Touch response become weak day by day. 4) It does not have cancel button/icon on second stage of dialed number ,which make voucher recharge difficult, or make incorrect input to customer call. 5) It support only 720P i.e. it does not support full HD. 6) Video recording does not support zoom function & recording is at 720p but still have black color in recording as compare to image capture. Screen vision always changing black to white and white to black vice versa. 7) Some time screen get black or dim after charging which need to make a restart to mobile to come to original. 8) (It does not have light sensor)Display does not glow many time after you remove it from ear which make call disconnect impossible still you remove the battery, as switch off or restart does not work at that time & call is connected so billing increases. 9) Net speed is too slow though it having 1.2Gz processor and 1GB RAM. 10) I am using inbuilt ringtone ,still it is having very low sound & does not come to know easily in traffic or T.V sound. >

May be the signal reception is slow... take it to a place where you'll get a good signal and check...If still your problem exists,
It may be the problem with your Device, but not Samsung. Return the device back as soon as possible... If it's already late, take it to the nearest service center.
> Net Speed depends on your network...but not on processor and RAM.
> Some device's sound is low...
> In spec's, they clearly stated that the device supports 720p display.

Friends this is the best mobile so faaaaaaaaa..................
Powered by a 1.2 GHz Dual Core and Android Jelly Bean, Galaxy Core is ultra-fast and ultra-powerful.

Now stay connected, multitask and do much more, effortlessly and at an unbelievably high-speed.
2G EDGE/GPRS (850/900/1,800/1,900MHZ)
3G HSPA 7.20/5.76 (900/2,100MHz)
WI-FI 802.11b/g/n 2.4GHz
WI-FI DIRECT Yes
BLUETOOTH PROFILES A2DP, AVRCP, GAP, HFP, HSP, OPP, HID, PAN, PBAP, MAP

Friends this is the best mobile so faaaaaaaaa..................
Powered by a 1.2 GHz Dual Core and Android Jelly Bean, Galaxy Core is ultra-fast and ultra-powerful.

Now stay connected, multitask and do much more, effortlessly and at an unbelievably high-speed.
2G EDGE/GPRS (850/900/1,800/1,900MHZ)
3G HSPA 7.20/5.76 (900/2,100MHz)
WI-FI 802.11b/g/n 2.4GHz
WI-FI DIRECT Yes
BLUETOOTH PROFILES A2DP, AVRCP, GAP, HFP, HSP, OPP, HID, PAN, PBAP, MAP

Heating effect and radiation is more......................................................................Price is not good