er... y not... it is dual activate mah... as long as the whatsapp is authorized within the phone y not...
I use my number but after i take out SIM put into another phone and leave the whatsapp phone wihtout SIM...
it still can receive and sent messages...

Coming from Nokia 3210, Nokia E61, Samsung P780, HTC HD2, iPhone 4 and Lenovo S890.

Playing for 7 days now... my review & comparison to daily-drive Alcatel Idol X:

A=Android
> iX custom-UI is horrible.
> P780 is more versatile.
! P780 wins.

B=Body-Built
> iX is sturdy but not premium. Slim bezel is irresistible.
> P780 hefty feeling is more premium but wider than iX.
! Draw.

C=Call quality
> iX is average. Static presents intermittently.
> P780 is much better without static issue.
! P780 wins.

D=Data
> iX has HSPA+ modules for both micro-SIMs are excellent and stable. Bluetooth is stable.
> P780 only HSDPA on SIM1 but no 3G for SIM2. Bluetooth is reliable.
! iX wins.

E=Email
> iX not flexible but working as intended.
> P780 email client is more reliable and suits daily routine.
! P780 wins.

F=Free-apps
> iX : Whatsapp, Shazam, Asphalt 7, Kingsoft Office, Evernote, TouchPal Keyboard.
> P780 : Asphalt 7, CamCard, Evernote, EverNote, Kingsoft Office, SuperCamera.
! iX wins due to Whatsapp.

G=Games
> iX excels but juice is the enemy. Thanks to MTK6589-Turbo chip.
> P780 is OK but laggy abit due to non-Turbo MTK6589.
! iX wins.

H=Hangouts
> iX video call for Skype, Google Hangouts, Tango etc. is acceptable for 2MP front facing camera.
> P780 also decent.
! Draw.

I=Internet
> iX default browser is smooth. No checker-board effect even heavy websites. 2GB RAM helps alot.
> P780 also decent but sometime lag on heavy webs. 1GB RAM needs Android 4it.4kat (ie. KitKat)
! iX wins.

J=Juice
> iX has 2000 mAh="mediocre". Claimed talk-time, stand-by time, etc. are questionable. Powerbank...?
> P780 has 4000 mAh which is its "trade-mark". It is now the powerbank for iX.
! P780 wins.

K=Kamasutra 
> iX vibrates with notification/ringtone. But vibrating too mild.
> P780 vibrates more than iX. You won't miss a call/notification during silent mode.
! P780 wins.

L=Loudspeaker
> iX is mediocre. Tiny and low treble.
> P780 more crisp.
! P780 wins.

M=Music
> iX has nothing unusual. Built-in Shazam app is a plus. FM radio is welcome.
> P780 is equal.
! Draw.

N=Navigation
> iX is working as expected. Lock satellite within 10 seconds. Waze is working normally.
> P780 is equal.
! Draw.

O=One-hand Operation.
> iX has slimmer bezels. 
> P780 is tad wider but I have "big" hands and "long" fingers    No further comment.
! Draw.

P=Picture
> iX has 13MP but camera features are limited. Pix and vids are above average. Colour re-production is more accurate.
> P780 has 8MP; acceptable pix and vids quality. Colour re-production is slightly off.
! iX wins.

Q=Quirks
> iX customised-Android is stable. No quirks. But UI needs to improve.
> P780 is decent and more intuitive.
! P780 wins.

R=Radio
> iX built-in FM radio works best in earphones.
> P780 FM radio and decent speakers is good for outdoors.
! P780 wins.

S=Sound
> iX is tiny even maximum due to low quality speaker.
> P780 is louder and more treble.
! P780 wins.

T=Texting
> iX Touchpal keyboard is brilliant. But Swiftkey is better.
> P780 native Google keyboard is more reliable.
! P780 wins.

U=User-Interface
> iX is smooth but not flexible. OneTouch UI needs new designer/architect.
> P780 is more intuitive.
! P780 wins.

V=Video
> iX 1080P video capture is acceptable. Auto-focus is acceptable.
> P780 is not as great as iX in general.
! iX wins.

W=WiFi
> iX performs on average. Not as great as iPhone(s). This is due to cheap MediaTek processor.
> P780 has non-Turbo MediaTek which performs slightly worse.
! iX wins.

X=X-factor
> iX has 5" 1080P screen with oleophobic DragonTrail Glass.
> P780 has 4000 mAh Lithium Polymer battery triples iX's battery performance.
! Draw.

Y=YouTube
> iX 441dpi screen and ear-phone is the way to go.
> P780 720P screen is not desirable.
! iX wins.

Z=Zero-figure
> iX intro-price at RM999-point-zero-zero is a smart move with medium specifications. Excellent for students.
> P780 (8GB) intro-price at RM899-point-zero-zero is also a value-buy for long-term investment.
! Draw.

iX conclusion : Buy it if desperate to have 5" 1080P IPS-OGS screen. It's like having Galaxy S4's or HTC One's screen.
P780 conclusion : Buy it if 4000 mAh battery is your priority. It is also a powerbank-on-the-go.

Scoreboard:
Alcatel OneTouch Idol X (aka iX) winning = 8
Lenovo IdeaPhone P780 (aka P780) winning = 11
Draw = 7

What i meant was Alcatel One Touch Idol X give free valid license of WhatsApp. No need to buy. It is bundle inside the phone right out of the box.

However,  P780 did not. We need to purchase WhatsApp even though it's cheap to pay.

Neither do I....