Which is the most popular application system for managing accounts
receivable in telecommunications companies worldwide?

The worldwide leader in Accounts Receivable software for the
telecommunications industry is SAP. A partial list of customers from
their website is found at:

http://www.sap.com/solutions/industry/telecom/customersuccesses.asp

Airtel Móvil S.A., Spain 
AT&T, Canada 
AT&T Canada Long Distance Services 
BCTEL, Canada 
Belgacom S.A., Belgium 
Bell Canada, Canada 
Binariang Sdn Bhd, Malaysia 
Bosch Telekom GmbH, Germany 
BOUYGUES TELECOM, France 
Cable Systems International, United States 
Compania de Telecomunicaciones, Chile 
COMPANIA PERUANA DE TELEFONOS, Peru 
Deutsche Telekom AG, Germany 
FRANCE TELECOM, France 
GTE Data Services Inc., United States 
Mannesmann Arcor, Germany 
max.mobil. Telekommunikation, Australia 
Mercury Communications Limited, Great Britian 
Omnitel , Italy 
Optus Communications Pty Ltd, Australia 
Pacific Telesis Group, United States 
PORTUGAL TELECOM, Portugal 
Post and Telecommunication, Papua New Guinea 
Post & Telekom Austria AG, Austria 
PT. Excelcomindo Pratama, Indonesia 
Proximus, Belgium 
Saskatchewan Telecommunication, Canada 
Siemens Optical Fibre Cables Ltd. 
SFR, France 
STARTEL S.A., Argentina 
STET Hellas S.A., Greece 
Telecom Corporation of NZ Ltd, New Zealand 
Telecom Eireann, Ireland 
TELECOM FINLAND, Finland 
TELECOM ITALIA MOBILE S.p.A., Italy 
Telecom PTT, Switzerland 
TELEFONICA DE ESPANA, S.A., Spain 
Telekom Malaysia Berhad, Malaysia 
Telenor AS, Norway 
Telephone & Data Systems, Inc., United States 
Telephone Organization of Thailand, Thailand 

A concise overview of all the players in the ERP market is found at:

http://techupdate.zdnet.com/techupdate/stories/main/0,14179,2844334,00.html

Some specifics of the SAP telecomm module can be found here:

http://www.sap.com/solutionmaps/Telecommunications/e987fe696cadd311bca70800060dfd76.htm

Along with some customer success stories:

http://www.sap.com/solutions/industry/telecom/customersuccesses.asp

Search terms used include:

ERP telecommunications "market share"
SAP A/R telecommunications
Fortune 1000 ERP "market share"

Thank you for using Google Answers

Dear marksalad

You have asked a big one here! Of course as everyone knows best is not
necessarily biggest. You might find it useful to look at details of
the award winners in the "Billing Systems 2002" Conference &
Exhibition held in May with 2000 participants, using the following
link and selecting 'Awards':
http://www.iir-billingsystems.com/

Hope you find this an interesting approach.