There is no Single Zip / Postal Code given by anybody for the Country "Bangladesh". We have Postal Code for various places of Dhaka like Tejgaon is "1215" and Motijheel/Dilkusha is "1000" and Chittagong Main (Agrabad) is "4000" etc.
Post codes are assigned on the basis of postal system and geographical distribution of population. Purpose of post code is to deliver articles at the earliest.
Postcode type and position:
4 digits to the right of the locality name, separated from the latter by a dash.
First Two Digits indicate: Head Post Office of Main Regional Town.
Second Two Digits indicate: Thana (Police Station) and Secondary Post Office.
Position of the Address on the envelope: Bottom right-hand corner.
Alignment of address lines: Right-aligned.
As we all know that these ZIP or Postal Codes are to indicate the nearest Post Office from where the letters/parcels may be delivered to your destination. Instead of reading the complete address, the Postal Deptt Sorters just see the ZIP/Postal Codes and sort the letters/parcels for easiness as well as making sure that the illegible handwritings may not make any hindrance at the first or successive points of Sorting, thereby avoiding wrong deliveries too.
Click on this link to view Post Code List at a glance:
However, the INTERNATIONAL CALLING CODE / Country Code of Bangladesh is 880 for tel/cell/mobile. Bangladesh Government allotted the following City Codes for dialing among the cities of Bangladesh, some are:
1. Chittagong 031
2. Dhaka (Dacca) 02
3. Khulna 041
4. Rangpur 0521
And so on...
Btw, International Country Codes used for long distance calling.
If you are calling from United States to Bangladesh then Dial:
011 + 880 + Area Code+ Tel #
Hope above helps.