Intercepting in Oman

Last June, the Guardian published a story about GCHQ tapping fiber-optic Internet cables around the globe, part of a program codenamed TEMPORA. One of the facts not reported in that story -- and supposedly the fact that the Guardian agreed to withhold in exchange for not being prosecuted by the UK authorities, was the location of the access points in the Middle East.
On Tuesday, the Register disclosed that they are in Oman:

The secret British spy base is part of a programme codenamed "CIRCUIT" and also referred to as Overseas Processing Centre 1 (OPC-1). It is located at Seeb, on the northern coast of Oman, where it taps in to various undersea cables passing through the Strait of Hormuz into the Persian/Arabian Gulf. Seeb is one of a three site GCHQ network in Oman, at locations codenamed "TIMPANI", "GUITAR" and "CLARINET". TIMPANI, near the Strait of Hormuz, can monitor Iraqi communications. CLARINET, in the south of Oman, is strategically close to Yemen.

Access is provided through secret agreements with BT and Vodafone:

British national telco BT, referred to within GCHQ and the American NSA under the ultra-classified codename "REMEDY", and Vodafone Cable (which owns the former Cable & Wireless company, aka "GERONTIC") are the two top earners of secret GCHQ payments running into tens of millions of pounds annually.

There's no source document associated with the story, but it does seem to be accurate. Glenn Greenwald comments:

"Snowden has no source relationship with Duncan (who is a great journalist), and never provided documents to him directly or indirectly, as Snowden has made clear," Greenwald said in an email. "I can engage in informed speculation about how Duncan got this document -­ it's certainly a document that several people in the Guardian UK possessed ­-- but how he got it is something only he can answer."

The reporter is staying mum on his source:

When Wired.co.uk asked Duncan Campbell -- the investigative journalist behind the Register article revealing the Oman location -- if he too had copies proving the allegations, he responded: "I won't answer that question -- given the conduct of the authorities."
"I was able to look at some of the material provided in Britain to the Guardian by Edward Snowden last year," Campbell, who is a forensic expert witness on communications data, tells us.

Campbell also published this on the NSA today.