011 is not part of the area code or country code, it is the access prefix for outbound international calls from North America (USA, Canada, etc.).
Telephone country code +501 is the Central American nation of Belize.
(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)
Little Rock, Arkansas, USA, is in area code 501 within the country code +1.
Country code +501 is Belize, in Central America.
The country code and area code of Mariestad, Sweden is 46, (0)501.
The area code 501 is used in the United States of America. It is used in the state of Arkansas. The area code includes Conway, Perry, Lonoke, Pulaski, Saline, Garland and Faulkner.
Until 1997, all of Arkansas was area code 501. In 1997, 870 split from 501, serving a broad swath including Pine Bluff, Texarkana, West Memphis, Jonesboro, Batesville, Harrison, and Arkadelphia. In 2002, area code 479 split from 501, serving northwestern Arkansas, including Fort Smith and Fayetteville. Area code 327 was announced as an overlay for 870, but it has been postponed indefinitely, probably to around 2018.
Message Sender might be from other country than yours. If that is just the area code then that is a Little Rock, Arkansas area code.
The country code and area code of Changhua, Taiwan is 886, 47.
The country code and area code of ChillÌÁn, Chile is 56, 42.
The country code and area code of Asturias, Spain is 34, 884.
The country code and area code of Arganil, Portugal is 351, 235.
The country code and area code of Badajoz, Spain is 34, 824.
The country code and area code of Alava, Spain is 34, 845.
The country code and area code of Gelephu, Bhutan is 975, 6.
The country code and area code of Baghdad, Iraq is 964, 1.