+255

Country Code: +255
International Call Prefix: 000
Trunk Prefix: 0

Until 1999, Tanzania, Kenya and Uganda shared a telephone numbering plan, in which subscribers were only required to dial the trunk code, area code and number. In that year, Tanzania adopted a new numbering plan. Calls to Kenya and Uganda require a regional prefix rather than having to use full international dialling. To call Kenya from Tanzania, subscribers dial 005 instead of +254, while to call Uganda, they dial 006 rather instead of +256. To call Tanzania from Kenya and Uganda, subscribers dial 007 instead of +255.

The NSN length is nine digits.

Geographic codes are in the range 20 to 29:

VoIP services begin with 41:

Mobile numbers start with 6 or 7:

Non-geographic numbering begins 8 or 9:

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Wikipedia