In this video i talk with Andrew Dyke from Pure IP around what Pure IP do and can offer around telephony and PSTN options for Skype for Business with or without SBCs. From global SIP trunking, Full ISDN replacement in 32 countries, CLI presentation, emergency services hosted CCE, Contact centres, web rtc solutions and Pure IP are also Skype for Business certified.
Ive come across and worked with Pure IP for SIP trunk solutions for Skype for Business and Lync deployments for customers but they offer more than SIP trunking and are a global provider. Check out all they offer here http://www.pure-ip.com/why-use-pure-ip
Martin Boam's Microsoft Blog 