The phrase "a sub office" is correct and usable in written English.
It can be used to refer to a smaller or secondary office that is part of a larger organization or company.
Example: "The company has several branches, but the main headquarters is located in New York, while a sub office operates in Los Angeles."
Alternatives: "a satellite office" or "a branch office".
The Northeast News, a free weekly published in Fort St .John, has a sub-office in Dawson Creek.
In order to deal with this they opened a sub-office in the town, run by John Harrison (1837 96), which continued to exist until the late 1880s.
Through its main office in Nouakchott and a sub-office in Bassikounou, UNICEF Mauritania's aims to reach all children, in every part of the country.
In January 1993 the Suva office became a sub-office of UNICEF Philippines until 1997 when it became the hub for a dedicated Pacific multi country office.
In February UNICEF opened a sub-office in Bouake in order to bring health & nutrition, water & environmental sanitation, basic education and child protection support closer to children and other vulnerable groups in the occupied zones.
A sub-office was also opened at the same time in Yamoussoukro, the political capital, and is now acting as an important logistics hub for UNICEF field operations in central, western and northern Côte d'Ivoire.
UNICEF South Africa inaugurates sub office in Cape Town Cape Town, 17 August 2007 - UNICEF South Africa today officially inaugurated its first sub office in the country to be located in the Western Cape Provincial Legislature building in Cape Town.
All these items were already prepositioned in the UNICEF sub office of Goma, some 350 kms south of Bunia.
They did, a sub-post office run by Noorie, while baby Hussein was born above the Muswell Hill shop.
The demonstration considers a sub-metered office building in Philadelphia with central heating and cooling equipment nearing replacement.
