The former Pompey favourite has not played since two substitute appearances for Aberdeen in the Scottish Premiership last season.
However, he was invited to train with Walsall in March, harbouring ambitions of winning a permanent deal.
Halford had been involved for two sessions before coronavirus shut down football.
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Yet the 35-year-old remains in touch with the League Two Saddlers, continuing to follow their training programmes.
And he’s keen to earn a future with Darrell Clarke’s team once through the other side.
He told The News: ‘Before this pandemic I had been training with Walsall.
‘They were looking at me to see if I could bring anything to the team and, once we are back in training, it will resume.
‘It was so good just to put my boots back on, get on grass and to kick a ball again. It made me realise just how much I missed doing that.
‘Since Aberdeen, I kind of accepted my career was over, so I was calling myself semi-retired. But I was hoping I would get another opportunity.
‘Then I got in touch with Marcus Stewart, the assistant at Walsall. I had played against him loads of times and he passed it onto the manager – who said “Come in”.
‘I am grateful for them even letting me come in and do training. While they didn’t say a deal is there in so many words, the way I look at it is a club wouldn’t invite someone to come in if they weren’t looking for something to improve the team.
‘If I can impress in training and do what I know I can – and get up to speed as quickly as possible – perhaps there’s a possibility in the long run.’
Halford was part of the Cardiff side which won promotion to the Premier League in 2017-18, making 16 appearances.
Since then, he has trained at West Brom and Luton, while joined Aberdeen in February 2019.
And he is keen to prolong his career.
Halford added: ‘It is down to me to pull my finger out and get back to the standard I want to be at, but, more importantly, a standard they are happy with.
‘Whether it could be a deal on the table or pay as you play, as long as I am in training and playing games, that’s all that matters.
‘I have never cared about money when it comes to football, I have always said if I could play for free I really would – and that shows the character I am.’