Interesting links
Australian websites
The Sound and Telecommunications Association Australasia (STAA) was formed in 2016 to oversee the operations of several hobby groups in Australia and New Zealand concerned with the collecting, preservation and history of sound and telecommunications equipment.
Australian Telecommunications museums (Vic, NSW, Qld). Contact info. 

Australasian Telephone Collectors Society. The ATCS now hosts the late Bob Estreich's site, "Bobs old phones" - a valuable resource for novice collectors.
Australian Historic Telephone Society. Melbourne based telephone collectors club.

The contact point for the WA Historic Telecommunications Society (a branch of the abovementioned AHTS).
An interesting Australian site with images, articles etc of early Australian electromechanical automatic exchange technologies.
The Vintage Wireless and Gramophone Club of WA. The main interests are wireless receivers and gramophones/phonographs but many members are also interested in telephones, televisions and a range of other audio/visual artefacts. The club meets monthly in suburban Perth WA.
These two sites give some good background to Australian telegraphy history.
http://telegramsaustralia.com/index.html
This is the site of an Australian business restoring and marketing old PMG telephone boxes, post boxes etc. The only Australian source as far as I know. Located in NSW.
Australian vintage payphone site. Includes detailed info. on red phones, gold phones and lots more.
UK Websites
A UK site that is well worth visiting. Sam has included some detailed dismantle/assemble photo-essays on some early phones also used in Australia.
An excellent UK site with a comprehensive Australian section.

Interesting site from the UK. It contains images, technical data, circuit diagrams and other information on a very wide range of British telephones and equipment. Australia shared a lot of equipment types with the UK, particularly up to the 1960s, so it will be very useful to Australian collectors.
Telephone Lines have been trading in antique, retro, designer, kiosks and fun telephones since 1972 and have a vast range of new and old telephones and spare parts available to buy online.
These are two small family businesses located in Yorkshire UK. The first  sells refurbished & serviced genuine 1970's vintage 746 Telephones. The 746 was the NZ Post Office mainstay in the last quarter of the 20th century. The second business is similar but its focus is on  early candlestick and Bakelite phones.
A UK mobile phone history site. Work in progress but may be worth keeping an eye on it.

USA and other world sites
The Antique Telephone Collectors Association, Headquartered in Kansas USA, its over 1000 active members are located throughout the United States, Canada, Europe, and Australia
The TCI Library was created by Remco Enthoven and is maintained by Telephone Collectors International, a non-profit organisation, as a public service. It is helping to preserve the history of telephony -- particularly fragile paper documents that may otherwise be lost to posterity. It contains a wide range of scanned catalogues, circuits and other information of great value to telephone collectors and restorers.
This USA based website is a very detailed resource for antique telephone collectors, and a showcase for telephone content.
An excellent USA resource owned by Richard Rose covering all aspects of Ericofon telephones.
Mobile phone museum in Dobsina, Slovakia. An article can be read here.
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A USA collector's site showing his antique and vintage telephones collected over 30 years. Many early & rare American telephones from the late 1800s to the 1970s are represented.  The main feature is the vast accumulation of "coin collectors" & payphones illustrating the (sometimes subtle) progression from the early coin collectors of the 1890s through the introduction of the 50A paystation around 1912 until the end of production of the 3 Slot around 1970.  Recently  added a new section dedicated to 1960 on payphones. 
This is an interesting "virtual" telephone collection site. It focusses on character, novelty and advertising phones mostly from the last quarter of the 20th century into the 21st c. A very good resource for collectors of this genre.
Ericsson historic catalogues
A very interesting site managed by Arwin Schaddelee in the Netherlands. He has a wide range of content including descriptions of antique through to recent European phones, restoration methods and some technical information. Mostly in English.