The fraud was uncovered after Summerhill, who has now been sacked from his job, attempted to sell some of the phones through website Mazuma Mobile.
Mazuma then contacted Vodafone to find out who the phones belonged to.
The NHS issues some staff, including community midwives, nurses, and on-call clinical staff, with iphones necessary to carry out their job.
But Summerhill is understood to have been ordering in more phones than necessary, then selling both new and used ones through Mazuma, second-hand goods site CEX and trade-in website Music Magpie.
He pleaded guilty to fraud while compromising his position of trust, over the period of almost one year from December 2016 to November 2017, when he appeared before magistrates in Teesside last week. The value of the fraud was £10,706.
He was sentenced to four months in prison, suspended for 24 months and ordered to pay a victim surcharge of £115 and costs of £85.
The sentence was suspended due to his previous good character, remorse and due to family circumstances.
He is understood to have made some admissions when interviewed by police.
A spokesperson for County Durham and Darlington NHS Foundation Trust said: “A former senior member of our IT team abused his position of responsibility and the trust placed in him by selling new and used mobile phones belonging to the Trust, for personal gain.
"As soon as suspicions were raised the member of staff was suspended and our counter fraud provider, Audit One, undertook an investigation before referring the case to the Crown Prosecution Service. The individual pleaded guilty to one count of fraud by abuse of position.
"Deception of this kind is rare and will not be tolerated.”